Answers
Answer:
[tex] S_6 = -63 [/tex]
Step-by-step explanation:
The sequence above is a geometric sequence.
The common ratio (r) = [tex] \frac{-6}{3} = \frac{12}{-6} = -2 [/tex]
The common ratio < 1, therefore, the formula for the sum of nth terms of the sequence would be: [tex] S_n = \frac{a_1(1 - r^n)}{1 - r} [/tex]
a1 = 3
r = -2
n = 6
Plug in the values into the formula
[tex] S_6 = \frac{3(1 - (-2^6)}{1 - (-2)} [/tex]
[tex] S_6 = \frac{3(1 - (64)}{1 + 2} [/tex]
[tex] S_6 = \frac{3(-63)}{3} [/tex]
[tex] S_6 = -63 [/tex]
Related Questions
A box is 90 cm long. Which of these is closest to the length of this box in feet?{1 inch= 2.54cm} (1 point)
Answers
Answer:
2.952755906 ft
Step-by-step explanation:
We need to convert 90 cm to inches
90 cm * 1 inch / 2.54 cm =35.43307087 inches
Now convert inches to ft
12 inches = 1ft
35.43307087 inches * 1 ft/ 12 inches =2.952755906 ft
What is 5 feet and 11 inches in inches
Answers
Answer:
60
Step-by-step explanation:
5 is 60 inch
A soccer player has made 3 of her last 10 field goals, which is a field goal percentage of 30%. How many more consecutive field goals would she need to make to raise her field goal percentage to 50%?
Answers
Answer:
4 consecutive goals
Step-by-step explanation:
If 3 of last 10 field goals = 30%
Which is equivalent to
(Number of goals scored / total games played) * 100%
(3 / 10) * 100% = 30%
Number of consecutive goals one has to score to raise field goal to 50% will be:
Let y = number of consecutive goals
[(3+y) / (10+y)] * 100% = 50%
[(3+y) / (10+y)] * 100/100 = 50/100
[(3+y) / (10+y)] * 1 = 0.5
(3+y) / (10+y) = 0.5
3+y = 0.5(10 + y)
3+y = 5 + 0.5y
y - 0.5y = 5 - 3
0.5y = 2
y = 2 / 0.5
y = 4
Therefore, number of consecutive goals needed to raise field goal to 50% = 4
find the 5th term in the sequence an=n÷n+1
Answers
Answer:
The 5th term of a sequence is defined as the term with n = 5. So for this sequence, a sub 5 = 5/6
There are four blue marbles, an unknown number of red (r) marbles, and six yellow marbles in a bag. Which expression represents the probability of randomly selecting a blue marble, replacing it, and then randomly selecting a red marble? StartFraction 4 over 10 EndFraction (StartFraction r over 10 EndFraction) StartFraction 4 over 10 r EndFraction (StartFraction 4 over 10 r EndFraction) StartFraction 4 over 10 + r EndFraction (StartFraction r over 10 + r EndFraction) StartFraction 4 over 10 r EndFraction (StartFraction r over 10 r EndFraction)
Answers
Answer:
4/ (10+r) * r/ (10+r)
Step-by-step explanation:
four blue marbles, an unknown number of red (r) marbles, and six yellow marbles in a bag = 4+r+6 = 10+r marbles
P( blue) = blue marbles / total marbles
= 4/ (10+r)
Then replace
P( r) = red marbles / total marbles
= r/ (10+r)
P( blue replace ,red) =P ( blue ) * P(red)
= 4/ (10+r) * r/ (10+r)
= 4r / ( 10+r) ^2
Answer:
C. 4/10+r (r/10+r)
Step-by-step explanation:
EDG20
find the range of the inequality 2e-3< 3e-1
Answers
Answer:
[tex]x = { - 1, 0,1 ,2 ...}[/tex]
Step-by-step explanation:
[tex]2e - 3 < 3e - 1 = 2e - 3e < - 1 + 3 = - 1e < 2 = e > - 2[/tex]
Hope this helps ;) ❤❤❤
Prove that if a and b are integers, then for any integer k one has (a,b) = (a + kb,b). (Hint: Show that they are mutually divisible.)
Answers
Answer:
The operation:
(a,b) is equal to the rest of the division of a by b.
Now, if we have:
(a + kb,b) = (a,b) + (k*b,b)
But if we have that k and b are integers, then:
(k*b)/b = k
So b divides k*b into a whole number, this means that (k*b,b) = 0
then:
(a + kb,b) = (a,b) + (k*b,b) = (a,b) + 0 = (a,b)
Write 11 numbers in a row so that the sum of any 3 consecutive numbers is negative, while the sum of all the numbers is positive.
Answers
Answer:
Step-by-step explanation:
Hello, if I take the following
2, 2, -5, 2, 2, -5, 2, 2, -5, 2, 2
The sum is 8*2-5*3=16-15=1 > 0
and
2 + 2 -5 < 0
2 - 5 + 2 < 0
-5 + 2 + 2 < 0
2 + 2 -5 < 0
2 - 5 + 2 < 0
-5 + 2 + 2 < 0
2 + 2 -5 < 0
2 - 5 + 2 < 0
-5 + 2 + 2 < 0
2 + 2 -5 < 0
2 - 5 + 2 < 0
Hope this helps.
Do not hesitate if you need further explanation.
Thank you
A survey asked, "How many tattoos do you currently have on your body?" Of the males surveyed, responded that they had at least one tattoo. Of the females surveyed, responded that they had at least one tattoo. Construct a % confidence interval to judge whether the proportion of males that have at least one tattoo differs significantly from the proportion of females that have at least one tattoo. Interpret the interval.
Answers
Complete Question
The complete question is shown on the first uploaded image
Answer:
The 95% interval for [tex]p_1 - p_2[/tex] is [tex]-0.0171 ,0.0411[/tex]
Option A is correct
Step-by-step explanation:
From the question we are told that
The sample size of male is [tex]n_1 = 1211[/tex]
The number of males that said they have at least one tattoo is [tex]r = 182[/tex]
The sample size of female is [tex]n_2 = 1041[/tex]
The number of females that said they have at least one tattoo is [tex]k = 144[/tex]
Generally the sample proportion of male is
[tex]\r p_1 = \frac{r}{ n_1}[/tex]
substituting values
[tex]\r p_1 = \frac{ 182}{1211}[/tex]
[tex]\r p_1 = 0.1503[/tex]
Generally the sample proportion of female is
[tex]\r p_2 = \frac{k}{ n_2}[/tex]
substituting values
[tex]\r p_2 = \frac{ 144}{1041}[/tex]
[tex]\r p_2 = 0.1383[/tex]
Given that the confidence level is 95% then the level of significance is mathematically represented as
[tex]\alpha =100-95[/tex]
[tex]\alpha =5\%[/tex]
[tex]\alpha =0.05[/tex]
Next we obtain the critical value of [tex]\frac{\alpha }{2}[/tex] from the normal distribution table , the value is
[tex]Z_\frac{\alpha }{2} = 1.96[/tex]
Generally the margin of error is mathematically represented as
[tex]E = Z_{\frac{\alpha }{2} } * \sqrt{\frac{\r p_1 (1- \r p_1)}{n_1} + \frac{\r p_2 (1- \r p_2)}{n_2} }[/tex]
substituting values
[tex]E = 1.96 * \sqrt{\frac{ 0.1503 (1- 0.1503)}{1211} + \frac{0.1383 (1- 0.1383)}{1041} }[/tex]
[tex]E = 0.0291[/tex]
The 95% confidence interval is mathematically represented as
[tex](\r p_1 - \r p_2 ) - E < p_1-p_2 < (\r p_1 - \r p_2 ) + E[/tex]
substituting values
[tex](0.1503- 0.1383 ) - 0.0291 < p_1-p_2 < (0.1503- 0.1383 ) + 0.0291[/tex]
[tex]-0.0171 < p_1-p_2 < 0.0411[/tex]
So the interpretation is that there is 95% confidence that the difference of the proportion is in the interval .So conclude that there is insufficient evidence of a significant difference in the proportion of male and female that have at least one tattoo
This because the difference in proportion is less than [tex]\alpha[/tex]
A work shift for an employee at Starbucks consists of 8 hours (whole).
What FRACTION (part) of the employees work shift is represented by 2
hours? *
Answers
Answer:
1/4 of an hour
Step-by-step explanation:
2 divided by 8 = 1/4
Answer:
1/4
Step-by-step explanation:
A whole shift is 8 hours
Part over whole is the fraction
2/8
Divide top and bottom by 2
1/4
Enter an expression that is equivalent to (6x2−1)+(x2+3)−2(x2−5)−15x2, combining all like terms. Use the on-screen keyboard to type the correct polynomial in the box below.
Answers
Answer:
Its 10x^2+12
Step-by-step explanation:
Answer:
-10X^2+12
Step-by-step explanation:
Take your time! :) Not important, but I would like to know, I'm writing flashcards so I can remember when I start back in school. Can you explain how to get the LCM of two numbers,GCF of two numbers, and what's the difference?
Answers
Answer:
The LCM of two numbers is the least common multiple. You want to find the least possible number that is divisible by the two numbers. So, you can list the factors of the two numbers. If there are factors that are repeated, put the repeated factors to the side. With the remaining factors, multiply the factors by each other and the repeated factors.
For example, let's try to find the least common multiple between 10 and 15.
Factors of 10: 2 * 5
Factors of 15: 3 * 5
The repeated factor is 5.
2 and 3 are left over. 2 * 3 = 6. 6 * 5 = 30. So, that is the least common multiple.
The GCF of two numbers is the greatest common factor. You want to find the greatest factor that is included in both numbers. So, again, you can list the factors of the two numbers and find the greatest factor that is repeated between the two numbers.
For example, let's try to find the greatest common factor between 30 and 45.
Factors of 30: 1, 2, 3, 5, 6, 10, 15, 30
Factors of 45: 1, 3, 5, 9, 15, 45
Between the two numbers, shared factors are 1, 3, 5, and 15. So, the greatest common factor is 15.
Hope this helps!
Find all values of x on the graph of f(x) = 2x3 + 6x2 + 7 at which there is a horizontal tangent line.
Answers
Answer:
the equation is not correct, u have to write like
ax'3+bx'2+cx+d
Answer:
x=-2 and x=0
Step-by-step explanation:
So I know it isn't x=-3 and x=0. So my guess is that it is x=0 and x=-2 and heres why.
First, I find the derivative of f(x)=2x^3+6x^2+7 which is 6x^2+12x
Then, I plugged in all the values of x's I had and I found out that you get 0 for -2 and 0 when you plug them in
So, in conclusion I believe the answer to be x=-2 and x=0
determine the results of the following operations
Answers
Answer:
[tex]\sqrt[3]{4}\times (\sqrt[3]{16}-10 )[/tex]
Step-by-step explanation:
Let be [tex]\sqrt[3]{64}-\sqrt[3]{32} \times \sqrt[3]{125}[/tex], this expression is simplified as follows:
1) [tex]\sqrt[3]{64}-\sqrt[3]{32} \times \sqrt[3]{125}[/tex] Given
2) [tex]\sqrt[3]{4^{3}}-\sqrt[3]{2^{5}}\times \sqrt[3]{5^{3}}[/tex] Definition of power
3) [tex](4^{3})^{1/3}-(2^{2}\cdot 2^{3})^{1/3}\times (5^{3})^{1/3}[/tex] Definition of n-th root/[tex]a^{b+c}= a^{b}\cdot a^{c}[/tex]/[tex](a^{b})^{c} = a^{b\cdot c}[/tex]
4) [tex]4 - (2^{2})^{1/3}\times 2\times 5[/tex] [tex]a^{b+c}= a^{b}\cdot a^{c}[/tex]/[tex](a\cdot b)^{c} = a^{c}\cdot b^{c}[/tex]
5) [tex]4 - 10\times 4^{1/3}[/tex] Multiplication/Definition of power
6) [tex]4^{1/3}\cdot (4^{2/3}-10)[/tex] Distributive property/[tex]a^{b+c}= a^{b}\cdot a^{c}[/tex]
7) [tex]\sqrt[3]{4}\times [(4^{2})^{1/3}-10][/tex] [tex](a^{b})^{c} = a^{b\cdot c}[/tex]/Definition of n-th root
8) [tex]\sqrt[3]{4}\times (\sqrt[3]{16}-10 )[/tex] Definition of power/Result
The MCAT is the admission exam that medical schools use as one of the criteria for accepting students. The exam is based on a scale of 0-45. The following data shows the MCAT scores for nine students.
32 36 29 31 30 35 34 26 30
The 35th percentile of this data set is:________
a. 31
b. 32
c. 31.5
d. 30
Answers
Answer:
d. 30
Step-by-step explanation:
The computation of the 35th percentile of this data set is shown below:
Before that first we have to series the number in ascending number
S. No Numbers
1 26
2 29
3 30
4 30
5 31
6 32
7 34
8 35
9 36
Now use the formula
Here n = 9
Percentile = 100
[tex]= \frac{35(9 + 1)}{100} \\\\[/tex]
= 3.5th
= 3th + 0.5 (4th - 3th)
= 3th + 0.5 (30 - 30)
= 3th + 0
= 30
Simplify 6.92 to the exponent of 1000
Answers
Answer:
Whatever is raised to the power of 0 is 1
SO the answer is 1
Let f(x) = x - 1 and g(x) = x^2 - x. Find and simplify the expression. (f + g)(1) (f +g)(1) = ______
Answers
Answer:
The simplified answer of the given expression is 1.
Step-by-step explanation:
When you see (f + g)(x), then it means that you are going to add f(x) and g(x) together. So, we are going to add the terms together that are given in the problem. We are also given the value of x which is 1. So, we are going to combine this information together so we can simplify the expression.
(f + g)(1)
f(x) = x - 1
g(x) = x²
(f + g)(1) = (1 - 1) + (1²)
Simplify the terms in the parentheses.
(f + g)(1) = 0 + 1
Add 0 and 1.
(f + g)(1) = 1
So, (f + g)(1) will have a simplified answer of 1.
An apartment building is infested with 6.2 X 10 ratsOn average, each of these rats
produces 5.5 X 10' offspring each year. Assuming no rats leave or die, how many additional
rats will live in this building one year from now? Write your answer in standard form.
Answers
Answer: 3.41x10^3
Step-by-step explanation:
At the beginning of the year, we have:
R = 6.2x10 rats.
And we know that, in one year, each rat produces:
O = 5.5x10 offsprins.
Then each one of the 6.2x10 initial rats will produce 5.5x10 offsprings in one year, then after one year we have a total of:
(6.2x10)*(5.5x10) = (6.2*5.5)x(10*10) = 34.1x10^2
and we can write:
34.1 = 3.41x10
then: 34.1x10^2 = 3.41x10^3
So after one year, the average number of rats is: 3.41x10^3
Find the solution of the inequality 5 > r - 3.
A) r<2
B) r = 2
C) r=8
(D) r < 8
Answers
Answer:
[tex]\huge\boxed{r<8}[/tex]
Step-by-step explanation:
[tex]5 > r - 3[/tex]
Adding 3 to both sides
[tex]5 + 3 > r[/tex]
[tex]8 > r\\OR \\r < 8[/tex]
Answer: D. r<8
Step-by-step explanation:
[tex]5>r-3[/tex]
add 3 to both sides
[tex]r-3+3<5+3[/tex]
[tex]5+3=8[/tex]
simplify
[tex]r<8[/tex]
Please answer this correctly without making mistakes
Answers
Answer:
355/12
Step-by-step explanation:
Answer:
355/12mi
Step-by-step explanation:
9 1/2 = 19/2
20 1/12 = 241/12
19/2 + 241/12 = 355/12mi
The formula for the area of a square is s2, where s is the side length of the square. What is the area of a square with a side length of 6 centimeters? Do not include units in your answer.
Answers
Answer:
36
step by step
given length=6
so area of square is given by s2 i.e 6^2
=6×6
=36 (Ans)
the rainfall R(t) (inmm) over the course of a year in bali, indonesia as a function of time t(in days) can be modeled by a sinusoidal expression of the form a*sin(b*t)+d. At t=0, in mid april, the expected daily rainfall is 2.3mm, which is the daily average value throughout the year. 1 quarter of the year leter, at t=91.25, when the rainfall is at its minimum, the expected daily value is 1.4mm. find R(t).
Answers
[tex]\bold{\text{Answer:}\quad R(t)=-0.96\sin\bigg(\dfrac{\pi}{182.5}t}\bigg)+2.3}[/tex]
Step-by-step explanation:
The equation of a sin function is: y = A sin (Bx - C) + D where
Amplitude (A) is the distance from the midline to the max (or min)Period (P) = 2π/B --> B = 2π/PC/B is the phase shift (not used for this problem)D is the vertical shift (aka midline)D = 2.3
It is given that t = 0 is located at 2.30. The sin graph usually starts at 0 so the graph has shifted up 2.3 units. --> D = 2.3
A = -0.96
The amplitude is the difference between the maximum (or minimum) and the centerline. A = 2.30 - 1.44 = 0.96
The minimum is given as the next point. Since the graph usually has the next point as its maximum, this is a reflection so the equation will start with a negative. A = -0.96
B = π/182.5
It is given that [tex]\frac{1}{4}[/tex] Period = 91.25 --> P = 365
B = 2π/P
= 2π/365
= π/182.5
C = 0
No phase shift is given so C = 0
Input A, B, C, & D into the equation of a sin function:
[tex]R(t)=-0.96\sin\bigg(\dfrac{\pi}{182.5}t-0}\bigg)+2.3[/tex]
2/5 ( 1/3 x− 15/8 )− 1/3 ( 1/2 − 2/3 x)
Answers
Answer:
16/45x-11/12
Step-by-step explanation:
Multiply across
2/15x-30/40-1/6+2/9x=
Get common denominators of like terms
6/45x+10/45x-9/12-2/12=
Combine like terms
16/45x-11/12
The simplified expression is: (16/45)x - (11/12)
To simplify the given expression, we'll follow the steps:
Step 1: Distribute the fractions through the parentheses.
Step 2: Simplify the expression by combining like terms.
Let's proceed with the simplification:
Step 1: Distribute the fractions through the parentheses:
2/5 * (1/3x - 15/8) - 1/3 * (1/2 - 2/3x)
Step 2: Simplify the expression:
To distribute 2/5 through (1/3x - 15/8):
2/5 * 1/3x = 2/15x
2/5 * (-15/8) = -15/20 = -3/4
So, the first part becomes: 2/15x - 3/4
To distribute -1/3 through (1/2 - 2/3x):
-1/3 * 1/2 = -1/6
-1/3 * (-2/3x) = 2/9x
So, the second part becomes: -1/6 + 2/9x
Now, the entire expression becomes:
2/15x - 3/4 - 1/6 + 2/9x
Step 3: Combine like terms:
To combine the terms with "x":
2/15x + 2/9x = (2/15 + 2/9)x
Now, find the common denominator for (2/15) and (2/9), which is 45:
(2/15 + 2/9) = (6/45 + 10/45) = 16/45
So, the combined x term becomes:
(16/45)x
Now, combine the constant terms:
-3/4 - 1/6 = (-18/24 - 4/24) = -22/24
To simplify -22/24, we can divide both numerator and denominator by their greatest common divisor (which is 2):
-22 ÷ 2 = -11
24 ÷ 2 = 12
So, the combined constant term becomes:
(-11/12)
Putting it all together, the simplified expression is:
(16/45)x - (11/12)
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Complete question is:
Simplify the given expression: 2/5 ( 1/3 x− 15/8 )− 1/3 ( 1/2 − 2/3 x)
What is the minimum sample size required to estimate a population mean with 90% confidence when the desired margin of error is 1.25
Answers
Complete Question
What is the minimum sample size required to estimate a population mean with 90% confidence when the desired margin of error is 1.25? The standard deviation in a pre-selected sample is 7.5
Answer:
The minimum sample size is [tex]n =97[/tex]
Step-by-step explanation:
From the question we are told that
The margin of error is [tex]E = 1.25[/tex]
The standard deviation is [tex]s = 7.5[/tex]
Given that the confidence level is 90% then the level of significance is mathematically represented as
[tex]\alpha = 100 - 90[/tex]
[tex]\alpha =10\%[/tex]
[tex]\alpha =0.10[/tex]
Next we obtain the critical value of [tex]\frac{\alpha }{2}[/tex] from the normal distribution table
The value is [tex]Z_{\frac{ \alpha }{2} } = 1.645[/tex]
The minimum sample size is mathematically evaluated as
[tex]n = \frac{Z_{\frac{\alpha }{2} * s^2 }}{E^2 }[/tex]
=> [tex]n = \frac{1.645^2 * 7.5^2 }{1.25^2 }[/tex]
=> [tex]n =97[/tex]
g A random sample of size 16 taken from a normally distributed population revealed a sample mean of 50 and a sample variance of 36. The upper limit of a 95% confidence interval for the population mean would equal:
Answers
Answer:
The upper limit is
[tex]k = 52.94[/tex]
Step-by-step explanation:
From the question we told that
The sample size is [tex]n = 16[/tex]
The sample mean is [tex]\= x = 50[/tex]
The sample variance is [tex]\sigma ^2 = 36[/tex]
For a 95% confidence interval the confidence level is 95%
Given that the confidence level is 95% then the level of significance is mathematically evaluated as
[tex]\alpha = 100 - 95[/tex]
[tex]\alpha = 5 \%[/tex]
[tex]\alpha = 0.05[/tex]
Next we obtain the critical value of [tex]\frac{\alpha }{2}[/tex] from the normal distribution table(reference- math dot armstrong dot edu), the value is
[tex]Z_{\frac{ \alpha }{2} } = 1.96[/tex]
Generally the margin of error is mathematically represented as
[tex]E = Z_{\frac{\alpha }{2} } * \frac{\sigma}{\sqrt{n} }[/tex]
Here [tex]\sigma[/tex] is the standard deviation which is mathematically evaluated as
[tex]\sigma = \sqrt{\sigma^2}[/tex]
substituting values
[tex]\sigma = \sqrt{36}[/tex]
=> [tex]\sigma = 6[/tex]
So
[tex]E = 1.96 * \frac{6}{\sqrt{16} }[/tex]
[tex]E = 2.94[/tex]
The 95% confidence interval is mathematically represented as
[tex]\= x - E < \mu < \= x + E[/tex]
substituting values
[tex]50 -2.94 < \mu <50 +2.94[/tex]
[tex]47.06 < \mu <52.94[/tex]
The upper limit is
[tex]k = 52.94[/tex]
Please answer this correctly without making mistakes
Answers
Answer:
5/12
Step-by-step explanation:
3/4-1/3=
9/12-4/12=
5/12
For a certain instant lottery game, the odds in favor of a win are given as 81 to 19. Express the indicated degree of likelihood as a probability value between 0 and 1 inclusive.
Answers
Answer: 0.81
Step-by-step explanation:
[tex]81:19\ \text{can be written as the fraction}\ \dfrac{81}{81+19}=\dfrac{81}{100}=\large\boxed{0.81}[/tex]
Evaluate the integral using integration by parts with the indicated choices of u and dv. (Use C for the constant of integration.) ∫4x2 lnx dx ; u= lnx , dv=4x 2dx
Answers
Take
[tex]u=\ln x\implies\mathrm du=\dfrac{\mathrm dx}x[/tex]
[tex]\mathrm dv=4x^2\,\mathrm dx\implies v=\dfrac43x^3[/tex]
Then
[tex]\displaystyle\int4x^2\ln x\,\mathrm dx=\frac43x^3\ln x-\frac43\int x^2\,\mathrm dx=\frac43x^3\ln x-\frac49x^3+C[/tex]
[tex]=\boxed{\dfrac49x^3(3\ln x-1)+C}[/tex]
The required integration is,
∫4x² lnx dx = (lnx) [(4/3)x³ + C₁] - (4/9)x³ + C
The given integral is,
∫4x² lnx dx
Using integration by parts, choose u and dv.
In this case, we choose u = lnx and dv = 4x²dx.
Using the formula for integration by parts, we have:
∫ u dv = uv - ∫ v du
Substituting the values of u and dv, we get:
∫4x² lnx dx = (lnx) (∫ 4x² dx) - ∫ [(d/dx)lnx] (∫4x² dx) dx
Simplifying the first term using the power rule of integration, we get:
∫ 4x² dx = (4/3)x³ + C₁
For the second term, we need to evaluate (d/dx)lnx,
Which is simply 1/x. Substituting this value, we get:
∫ [(d/dx)lnx] (∫4x² dx) dx = ∫ [(1/x) ((4/3)x³ + C₁)] dx
Simplifying this expression, we get:
∫4x² lnx dx = (lnx) [(4/3)x³ + C₁] - ∫ [(4/3)x³/x] dx
Using the power rule of integration again, we get:
∫4x² lnx dx = (lnx) [(4/3)x³ + C₁] - (4/9)x³ + C
Where C is the constant of integration.
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(a) Five friends are in a netball squad. In each game during the 21-round season, at least 3 of them are picked in the team. Prove that there will be at least 3 matches in which the same three friends are selected to play.
(b) How does the answer change if there are six friends instead of 5?
PLS ANSWER FAST!!!!
Answers
Answer:
(a) there are 10 sets of 3 friends, so in 21 games, at least one set must show 3 times
(b) there are 20 sets of 3 friends, so in 21 games, at least one set must show 2 times.
Step-by-step explanation:
(a) The number of combinations of 5 things taken 3 at a time is ...
5C3 = 5!/(3!·2!) = 5·4/2 = 10
There can be 10 games in which the same 3 friends do not show up. There can be 10 more games such that the same 3 friends show up exactly twice. In the 21st game, some set of 3 friends must show up 3 times.
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(b) The number of combinations of 6 things taken 3 at a time is ...
6C3 = 6!/(3!·3!) = 6·5·4/(3·2) = 20
Hence, there can be 20 games in which the same 3 friends do not show up. In the 21st game, some set of 3 friends will show up a second time.
Prove that for all integers m and n, m - n is even if, and only if, both m and n are even or both m and n are odd.
Answers
Answer:
Below
Step-by-step explanation:
Suppose that m and n are both even numbers.
So we can express them as the product of 2 and another number.
● n = 2×a
● m = 2×b
● m-n = 2b-2a
● m-n = 2(b-a)
m-n is an even number since it is divisible by 2.
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Suppose that both n and m are odd numbers.
● n = 2a+1
● m = 2b+1
● m-n = 2b+1-(2a+1)
● m-n = 2b+1-2a-1
● m-n = 2b-2a
● m-n = 2(b-a)
So m-n is even since it is divisible by 2.
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Suppose that m is odd and n is even ir vice versa
● n = 2a or n= 2a+1
● m = 2b+1 or m = 2b
● m-n = 2b+1-2a or m-n = 2b-2a-1
● m-n = 2(b-a) +1 or m-n = 2(b-a)-1
In both cases m-n isn't even.
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So m-n is even if and only if m and n are odd or m and are even
Answer:
Case 1
both m and n are even
Therefore m/2 and n/2 are integers
Then,
m-n
=2(m/2 - n/2)
Since m/2 and n/2 are integers
Then m/2 - n/2 will be an integer
Therefore,
m-n = 2(Z)
Where Z is an integer
Since 2 is a factor of m-n
Therefore m -n is even
Case 2
Both m and n are odd
m-n
= 2(½m - ½n)
When an odd number is divided by 2 it gives an integer and a remainder of 1
Therefore
½m = Y + ½
And
½n = Z + ½
Where Y and Z are integers
Then
m-n = 2(Y+½-Z-½)
= 2(Y-Z)
Y-Z will also be an integer
m-n= 2A
Therefore m-n is even
Case 3
One is odd and the other even
m-n = 2(m/2 - n/2)
Assume m is even and n is odd
From the discussions above
m-n = 2(Y - Z - ½)
m-n = 2(A - ½)
Hence m-n is not even because when is divided by two it doesn't give an integer.
Therefore for all integers m and n, m - n is even if, and only if, both m and n are even or both m and n are odd.
