Find the sum Sn of the first n terms from the given sequence.
1, 1+2, 1+2+3, 1+2+3+4, ...
Please show your work and use Sigma Notation too. Thank you!​

Answers

Answer 1

The Sequence:

1 , 1+2 , 1+2+3 , 1+2+3+4, ...

here, every term is an AP. finding the general formula for the sum of the elements of each term is:

Sₙ = [tex]\frac{x}{2}(2a + (x-1)d)[/tex]        [where x = number of term, a = first term and d = common difference]

here, the first term is always 1 and so is the common difference.

Sₙ = [tex]\frac{x}{2}(2 +x-1)[/tex]

Sₙ = [tex]\frac{x}{2}(1 +x)[/tex] = [tex]\frac{1}{2}(x + x^{2})[/tex]

which is the formula for a general term in our series

now, we need to find the sum of the first n terms of this series

[tex]\displaystyle\sum_{x=1}^{n} [\frac{1}{2}(x + x^{2})][/tex]

[tex]\displaystyle\frac{1}{2} [\sum_{x=1}^{n} (x) + \sum_{x=1}^{n}(x^{2})][/tex]

in this formula, for the first term, it's just an AP from x = 1 to x = n

for the second term, we have a general formula [tex]\frac{n(n+1)(2n+1)}{6}[/tex]

[tex]\frac{1}{2}[\frac{n}{2}(2a + (n-1)d)+ \frac{n(n+1)(2n+1)}{6} ][/tex]

in this AP (first term), the first term and the common difference is 1 as well

[tex]\frac{1}{2}[\frac{n}{2}(2 + n-1)+ \frac{n(n+1)(2n+1)}{6} ][/tex]

[tex]\frac{1}{2}[\frac{n}{2}(n+1)+ \frac{n(n+1)(2n+1)}{6} ][/tex]

[tex][\frac{n}{4}(n+1)+ \frac{n(n+1)(2n+1)}{12} ][/tex]

[tex]\frac{n}{4}(n+1) [1+\frac{(2n+1)}{3} ][/tex]

[tex]\frac{n}{4}(n+1) [\frac{(3+2n+1)}{3} ][/tex]

[tex]\frac{n}{4}(n+1) [\frac{(2n+4)}{3} ][/tex]

[tex]\frac{n}{2}(n+1) [\frac{(n+2)}{3} ][/tex]

[tex]\frac{n(n+1)(n+2)}{6}[/tex]

which is the sum of n terms of the given sequence


Related Questions

Simplify the expression by combining like terms:

8x + 3y + 2x^2 + 6y^2 + 7 =

a
10x^2 + 9y^2 + 7
b
8x + 3y + 2x^2 + 6y^2 + 7
c
11xy + 8xy^2 + 7

Answers

Answer:

8x + 3y + 2x^2 + 6y^2 + 7 =

Step-by-step explanation:

8x + 3y + 2x^2 + 6y^2 + 7 =

Combine like terms

There are no like terms

8x + 3y + 2x^2 + 6y^2 + 7 =

Let's combine

8x+3y+2x²+6y²+7

No like terms present

We may arrange in order of degrees.

2x²+6y²+8x+3y+7

Simplify square root of -200

Answers

Answer:

14.1421356i

Step-by-step explanation:

hope it helps

i need helpp !! ill mark brainliest !

Answers

393/1000. i think, sorry. :c

Given that
a
= 3 cm and
b
= 21 cm, work out
θ
rounded to 1 DP.

Answers

Answer:

I am sorry I not no

this question

Step-by-step explanation:

sorry dear friend

help me please????????

Answers

Answer:

c

Step-by-step explanation:

Option c is correct. All points are equally spaced from the line x=1 as their images do. They are symmetric about the line x=1. For instance, point A and A' are both 3 units from the line x=1.

Option a and B are wrong as we cannot see and swapping of x and y coordinates to a point.

For option d, only point A is shifted 6 units to the left to A', but point B shifted 8 units to B'. Incorrect.

one half of a number plus 7

Answers

Answer:

1/2n + 7

n =  unkown number

Step-by-step explanation:

Answer:

1/2(x) + 7

Step-by-step explanation:

x= unknown number

Find the coordinates of the image of J (−5, −1) after the translation (x, y) → (x − 2, y).

A. (−7, −3)
B. (−5, −3)
C. (−3, −1)
D. (−7, −1)

Answers

Its D.(-7,-1)

Hope it helpss

The coordinates of the image of J (−5, −1) after the translation (x, y) → (x − 2, y) will be (−7, −1). Then the correct option is D.

What is a transformation of a point?

A spatial transformation is each mapping of feature space to itself and it maintains some spatial correlation between figures.

The rule of the translation is given below.

(x, y) → (x − 2, y)

The coordinates of the image of J (−5, −1). Then the location of the point J after the translation will be

(x, y) → (x − 2, y)

(−5, −1) → (−5 −2, −1)

(−5, −1) → (−7, −1)

The coordinates of the image of J (−5, −1) after the translation (x, y) → (x − 2, y) will be (−7, −1). Then the correct option is D.

More about the transformation of a point link is given below.

https://brainly.com/question/27224339

#SPJ2

The Coal Utility Company is burning coal to produce electricity. The following cost function illustrates the cost in dollars (C) of removing t% of the hazardous toxins generated from burning coal. What happens to the cost as t approaches 100?
C= 55,000t/100-t for 0 ≤ t < 100

A The cost continues to increase.
B The cost continues to decrease.
C The cost approaches $0.
D The cost approaches $55,000.

Answers

Answer:

the cost continues to increase

Step-by-step explanation:

the cost (C) approaches infinity (or becomes very large) as t approaches 100%. Thus, the correct answer is: A. The cost continues to increase.

To determine what happens to the cost (C) as t approaches 100%, we can take the limit of the cost function as t approaches 100.

The cost function is given as: [tex]\[ C = \frac{55,000t}{100 - t} \][/tex]

Now, let's find the limit of C as t approaches 100:[tex]\[ \lim_{{t \to 100}} C = \lim_{{t \to 100}} \frac{55,000t}{100 - t} \][/tex]

To find this limit, we can use direct substitution:[tex]\[ \lim_{{t \to 100}} \frac{55,000 \times 100}{100 - 100} = \lim_{{t \to 100}} \frac{5,500,000}{0} \][/tex]

Since the denominator approaches 0 as t approaches 100, the limit is undefined (infinite).

Therefore, the cost (C) approaches infinity (or becomes very large) as t approaches 100%. Thus, the correct answer is: A. The cost continues to increase.

To know more about infinity:

https://brainly.com/question/31331496

#SPJ3

x² + 4x from 5x² + x

Answers

That is,

(5x sq + x) - (x sq + 4x)

5x sq + x - (x sq + 4x)

5x sq - x sq + x - 4x

4x sq - 3x

What does the term "cube root" mean?

Answers

You can define the cube root of a number as a special value that. For example, 3 × 3 × 3 equals 27, so the cube root of 27 is 3.

Describe a relationship between two sets that you can describe mathematically

Answers

Answer:

LOVE and CARING for each other

Step-by-step explanation:

Mrs. Eskew saved her money for 32 years and had $4,119,184 in the bank. She used her money to go a vacation for a month and spent $978,349. How much did she have left after her vacation?

Answers

Answer:

$3,140,835

Step-by-step explanation:

4,119,184-978,349=3,140,835

hope this helped!

Explain how you can use absolute value to tell whether
the sum of two integers is positive or negative.

Answers

Answer:

Let the integers are p and q.

In case both integers are positive or negative, you add the numbers up and apply their sign to the sum.

Examples:

10 + 88 = 98-20 + (-15) = -35

In case one of the integers is negative and one positive.

p < 0, q > 0

Use absolute value in this case.

Subtract the numbers and apply the sign of the number with the greater absolute value.

Examples:

- 10 + 15 = |15 - 10| = |5| = 5- 15 + 10 = - |15 - 10| = - |5| = -5

Step-by-step explanation:

Let the numbers be x and y

If both are of same signs then

|x + y| = x + y

-|x + y| = -(x + y) = -x - y

If one is negative and one is positive

-|x + (-y)| = -|x - y| = -x + y

-|y + (-x)| = -|y - x| = -y + x

2 = 2.27 - m/4

I am so bad at math, lol! ^^ HELP ME PWEASE!

Answers

Answer:

m = 1.08

Step-by-step explanation:

Subtract 2.27 from both sides.

2 - 2.27 = -m/4

Simplify  2 - 2.27 to  -0.27.

-0.27 = -m/4

Multiply both sides by 4

-0.27 × 4 = -m

Simplify  -0.27 × 4 to -1.08.

-1.08 = -m

Multiply both sides by -1 (-m is also known as -1)

1.08 =m

Answer:

m = 1.08

Step-by-step explanation:

Basically, we can start off by finding the difference between 2 and 2.27(which is 0.27). Then we can see that 0.27 is equal to m/4. Since 0.27*4=1.08, we can see that m=1.08.

At a competition with 7 runners, medals are awarded for first, second, and
third places. Each of the 3 medals is different. How many ways are there to
award the medals?
Decide if this is a permutation or a combination, and find the number of ways
to award the medals.

Answers

Answer:

35 different combinations

Step-by-step explanation:

This would be a combination because the same person cannot get all three medals so permutation is not the correct way to calculate this. We use the formula C(n,r)=(nr)=n!(r!(n−r)!)=? where n is the number of total objects and r is the number of objects taken from the total.

brainliest pls . . . uwu

Pls help how do I solve this?

Answers

multiply length by width ( 5 x 4.2x^2-3xy) to get 21x^2 -15xy as your final answer

Answer:

area is just multiplication of sides so..

(4.2x^2 - 3xy) (5)

= 21 x^2 - 15 xy

doneeeeee

Which graph shows the function f(x) = x with an input of f(x – 3)?

Answers

Can’t answer if you don’t have a graph picture, but put it into your graphing calculator and you should get the answer

-2x + 9x5 + 1 - 9x2
What’s the answer to this someone help plz

Answers

Answer:

factored = -2(x-14) Simplified= -2x+28

Step-by-step explanation:

MARKING BRAINLIEST !! using the distance formula falculate the perimeter of the triangle below
a. 27.9 units
b. 24.3 units
c. 25.7 units
d. 28.2 units ​

Answers

Answer:

a

Step-by-step explanation:

i didn't use the distance formula, instead i used the pythagrean theorum. i counted the units for the legs, and made three smaller triangle and solved them to find the lengths of the hypotenuse and the added the three of those together to find the perimiter of the original triangle

Help anyone can help me do this question,I will mark brainlest.​

Answers

Answer:

Step-by-step explanation:

E ⊂ F ⊂ G

Brooke spent 3/4 hours playing her flute each day for 7 days. How many hours did she play her flute in all

Answers

Answer:

5 and 1/4 hours or 5 hours and 15 minutes

Step-by-step explanation:

She played her flute 3/4 hours every day for 7 days, so to find the total number of hours we can multiply 3/4 by 7 to get 21/4.  This is equal to 5 and 1/4 hours, or 5 hours and 15 minutes.

Answer:  5.25 hrs

Step-by-step explanation:  3/4 of an hour is 45 min.  45 min x 7 days is 315 min which is 5 hours and 15 min or 5.25 hrs

Rational numbers include whole numbers, integers, fractions, and some decimals?

Answers

Answer:

TRUE

Step-by-step explanation:

this is true.

rational= ratio

can anyone help me solve this function please?

Answers

Answer:

f(-5) = 19

Step-by-step explanation:

f(t) = -3t+4

Let f(t) = 19

19 =  -3t+4

Subtract 4 from each side

19 - 4 =-3t+4-4

15 = -3t

Divide each side by -3

15/-3 = -3t/-3

-5 = t

Answer:

the answer is -5

Step-by-step explanation:

F(t)=-3(t)+4

it told you that F(t) is equal to 19

so -3*-5=15+4=19

A goat is grazing outside of a rectangular barn that has dimensions 20 ft by 30 ft.
He's tied to a corner of the barn with a 12 ft rope. Find the grazing area of the goat.

Answers

Answer:

108π  ft² or  339.29 ft²

Step-by-step explanation:

Refer to attached picture.

The grazing area of the goat is 3/4 of area of circle with 12 ft radius:

A = 3/4(πr²) = 3/4(π*12²) = 108π  or  339.29 ft²

Tied to the corner

Means 1part among 4parts of circle or a quarter area

So grazing field

πr²-1/4πr²3/4πr²3/4(12)²π3/4(144)π108π339.3ft²

the number 126 is divisible by what numbers ? 2,3,4,5,6,9,10

Answers

Answer:

1,

Step-by-step explanation:

You may also be interested to know that all the numbers that 126 is divisible by are also known as the factors of 126. Not only that, but all the numbers that are divisible by 126 are the divisors of 126.

Is the relation a function? Explain


Set-builder notation?


Domain/range?

Answers

Answer:

doamin = set builder nation

Answer:

domain= set builder notation

What is one of the best ways to stop procrastinating and study More

Answers

Answer:

use the two minute rule. you tell yourself you will study for two minutes or ten minutes and then if you're in a flow you keep going. hope this helps :)

Determine whether each relation is a function

Please help I dont wanna fail math this year

Thanks

(I am in Algebra 1 btw)

Answers

I don’t know heh but try scanning it

Xian and his cousin Kal both collect stamps. Xian has 52 stamps, and Kal has 68 stamps. The boys recently
joined different stamp-collecting dubs. Xian's club will send him 20 new stamps per month. Kai's club will
send him 16 new stamps per month. After how many months will Xlan and Kal have the same number of
stamps? How many stamps will each have?

Answers

Answer:

In 4 months, they will both have 132 stamps.

Step-by-step explanation:

Let x = # of months

52 + 20x = 68 + 16x

4x = 16

x = 4

Plug x value into both expressions and see if it checks out

52 + 20(4) = 68 + 16(4)

52 + 80 = 68 + 64

132 = 132

Perform the indicated operations. Write the answer in standard form, a+bi.
5 - 3i / -2-9

Answers

[tex] \huge \boxed{\mathfrak{Answer} \downarrow}[/tex]

[tex] \large \bf\frac { 5 - 3 i } { - 2 - 9 } \\ [/tex]

Subtract 9 from -2 to get -11.

[tex] \large \bf \: Re(\frac{5-3i}{-11}) \\ [/tex]

Divide 5-3i by -11 to get [tex]\sf-\frac{5}{11}+\frac{3}{11}i \\ [/tex].

[tex] \large \bf \: Re(-\frac{5}{11}+\frac{3}{11}i) \\ [/tex]

The real part of [tex]\sf-\frac{5}{11}+\frac{3}{11}i \\ [/tex]is [tex]\sf-\frac{5}{11} \\ [/tex].

[tex] \large \boxed{\bf-\frac{5}{11} \approx -0.4545..} \\ [/tex]

Answer:

[tex] \frac{5 - 3i}{ - 2 - 9} \\ = \frac{ 5 - 3i}{ - 11} \\ = \frac{5}{ - 11} + \frac{3i}{11} \\ thank \: you[/tex]

Other Questions
5.4 - (9.5 - 8) - 2.5 (pls help and explain pls) PLEASE HELP................ Please help !!!! thank youuu Write 4 3/7 as a decimal.Enter your answer as a decimal rounded to the nearest hundredth, like this: 3.14 What is direct testing in esl 350 rounded to the nearest hundred is Find the value of the expression when x = 4 and y = 6.8x + 2y + 3 Question 2 (1 point)You go to the office and ask the secretary a question.O Usted 4x-2=18x+5 Show ur work Change the following fraction to a decimal. 8 4/5 = ? Write sentences on these topics withthe present perfect.1. Something you have learned lately2. Something you've wanted to do all your life3. A friend you haven't seen lately4. Countries you have visited so far5. The happiest life events so far What's Centripetal force................ how has malaria affected the economic in Cambodia Summarize the central ideas of the Iroquois Constitution. Which of these answers describes a scientific law?(Pls) enter the range of values for x: What are chemical contaminants?1)Homemade soaps. 2)Restaurant grade cleaners. 3)Alcohol. 4)Recreational drugs. HELP ASAP!!! The line (y-1)=(2/3)(x+1) contains point (a,-3). What is the value of a? Showyour work. Grace and her dad are planning to attend the state fair. An adult ticket is $15.00. The price of an adult ticket is one half the price of a student ticket plus $8.00. Write an equation to determine how much Grace will pay for a student ticket. one halfx + 8 = 15 one halfx 8 = 15 one halfx + 15 = 8 one halfx 15 = 8 Give an example of a non-biological chemical reaction that involves carbon. Name the process that converts a solid compound into a gas.