Answers
1. The given equation is probably supposed to read
y'' - 2y' - 3y = 64x exp(-x)
First consider the homogeneous equation,
y'' - 2y' - 3y = 0
which has characteristic equation
r² - 2r - 3 = (r - 3) (r + 1) = 0
with roots r = 3 and r = -1. Then the characteristic solution is
[tex]y = C_1 e^{3x} + C_2 e^{-x}[/tex]
and we let y₁ = exp(3x) and y₂ = exp(-x), our fundamental solutions.
Now we use variation of parameters, which gives a particular solution of the form
[tex]y_p = u_1y_1 + u_2y_2[/tex]
where
[tex]\displaystyle u_1 = -\int \frac{64xe^{-x}y_2}{W(y_1,y_2)} \, dx[/tex]
[tex]\displaystyle u_2 = \int \frac{64xe^{-x}y_1}{W(y_1,y_2)} \, dx[/tex]
and W(y₁, y₂) is the Wronskian determinant of the two fundamental solutions. This is
[tex]W(y_1,y_2) = \begin{vmatrix}e^{3x} & e^{-x} \\ (e^{3x})' & (e^{-x})'\end{vmatrix} = \begin{vmatrix}e^{3x} & e^{-x} \\ 3e^{3x} & -e^{-x}\end{vmatrix} = -e^{2x} - 3e^{2x} = -4e^{2x}[/tex]
Then we find
[tex]\displaystyle u_1 = -\int \frac{64xe^{-x} \cdot e^{-x}}{-4e^{2x}} \, dx = 16 \int xe^{-4x} \, dx = -(4x + 1) e^{-4x}[/tex]
[tex]\displaystyle u_2 = \int \frac{64xe^{-x} \cdot e^{3x}}{-4e^{2x}} \, dx = -16 \int x \, dx = -8x^2[/tex]
so it follows that the particular solution is
[tex]y_p = -(4x+1)e^{-4x} \cdot e^{3x} - 8x^2\cdot e^{-x} = -(8x^2+4x+1)e^{-x}[/tex]
and so the general solution is
[tex]\boxed{y(x) = C_1 e^{3x} + C_2e^{-x} - (8x^2+4x+1) e^{-x}}[/tex]
2. I'll again assume there's typo in the equation, and that it should read
y''' - 6y'' + 11y' - 6y = 2x exp(-x)
Again, we consider the homogeneous equation,
y''' - 6y'' + 11y' - 6y = 0
and observe that the characteristic polynomial,
r³ - 6r² + 11r - 6
has coefficients that sum to 1 - 6 + 11 - 6 = 0, which immediately tells us that r = 1 is a root. Polynomial division and subsequent factoring yields
r³ - 6r² + 11r - 6 = (r - 1) (r² - 5r + 6) = (r - 1) (r - 2) (r - 3)
and from this we see the characteristic solution is
[tex]y_c = C_1 e^x + C_2 e^{2x} + C_3 e^{3x}[/tex]
For the particular solution, I'll use undetermined coefficients. We look for a solution of the form
[tex]y_p = (ax+b)e^{-x}[/tex]
whose first three derivatives are
[tex]{y_p}' = ae^{-x} - (ax+b)e^{-x} = (-ax+a-b)e^{-x}[/tex]
[tex]{y_p}'' = -ae^{-x} - (-ax+a-b)e^{-x} = (ax-2a+b)e^{-x}[/tex]
[tex]{y_p}''' = ae^{-x} - (ax-2a+b)e^{-x} = (-ax+3a-b)e^{-x}[/tex]
Substituting these into the equation gives
[tex](-ax+3a-b)e^{-x} - 6(ax-2a+b)e^{-x} + 11(-ax+a-b)e^{-x} - 6(ax+b)e^{-x} = 2xe^{-x}[/tex]
[tex](-ax+3a-b) - 6(ax-2a+b) + 11(-ax+a-b) - 6(ax+b) = 2x[/tex]
[tex]-24ax+26a-24b = 2x[/tex]
It follows that -24a = 2 and 26a - 24b = 0, so that a = -1/12 = -12/144 and b = -13/144, so the particular solution is
[tex]y_p = -\dfrac{12x+13}{144}e^{-x}[/tex]
and the general solution is
[tex]\boxed{y = C_1 e^x + C_2 e^{2x} + C_3 e^{3x} - \dfrac{12x+13}{144} e^{-x}}[/tex]
Related Questions
a 25 -ft ladder rests against the side of a house. the distance between the top of the lader and the ground is 17 ft more than the distance between the base od the ladder and the bottom of the house. find both distances.
Answers
Answer:
Step-by-step explanation:
x² + (x + 17)² = 25²
x² + x² + 34x + 289 = 625
2x² + 34x - 336 = 0
x² + 17x - 168 = 0
x = (-17 ±√(17² - 4(1)(-168))) / (2(1))
x = 7 or - 24 the negative distance makes no sense, but if we plug our good answer of 7 ft in for the base length, the height comes out to be + 24 ft
base = 7 ft
height = 24 ft
What is 1/3÷1/2 math answers?
Answers
Answer:
= [tex]\frac{2}{3}[/tex]
Step-by-step explanation:
Result in decimals: 0.66666666666667
x = mutiply
[tex]=\frac{1}{3} x\frac{2}{1}[/tex]
[tex]\frac{1 x 2}{3 x 1 }[/tex]
= [tex]\frac{2}{3}[/tex]
(Hope this helps can I pls have brainlist (crown)☺️)
4 x ( 2 + 5 )^2 - 5^2
Answers
=4*49-25
=196-25
=171
solve the inequality x-3 < 3x -7
Answers
Answer:
x > 2 or 2 < x
Step-by-step explanation:
x-3 < 3x-7
-3 < 2x-7
4 < 2x
2 < x
x > 2
Sabrina has eight boxes of crayons, with ten crayons in each box. She uses twelve crayons. How many crayons does she
have left?
Answers
Answer:
68
Step-by-step explanation:
8 boxes. 10 per one box. 8×10=80
80-12= 68
Which inequality represents this sentence?
A number is no less than 48.
n < 48
n > 48
n < 48
n>48
Answers
The inequality that can be used to represent the information that a number is no less than 48 will be n > 48.
Inequality simply means a mathematical expression that is used in which the sides aren't equal to each other.
It should be noted that the expression that a number is no less than 48 means the number is greater than 48. Therefore, the inequality is n > 48.
Read related link on:
https://brainly.com/question/25701252
Answer: The correct answer is n≥48
Step-by-step explanation: Give me the brainiest
2/3 of a cup of batter can make 5/6 of a batch of pancakes. How many cups of water are needed to make one batch of pancakes?
Answers
Answer:
1 11/12 cups of water
Mr. and Mrs. Bruce took a boat trip which left Cala for Friends’ Island at 11:45 in the morning. The trip lasted for 1 hour and 20 mins. When did they arrive at Friends’ Island?
Answers
cual de estas fracciones es mayor que 2/5?explica como lo has averiguado
Answers
Answer:
33333
Step-by-step explanation:
negative seven times a number is negative two hundred forty five. what is the number?
pleasee i need help
Answers
Answer:
35
Step-by-step explanation:
since i couldn't answer before
Simplify 10^9 ÷ 10^7
Answers
Answer:
10^2
Step-by-step explanation:
10^9/10^7 is the same as 10^9*10^-7 if you multiply two same bases you can add there exponents. So, 9+(-7)=2. So, it’s 10^2
Answer:
100
Step-by-step explanation:
Hope it helps
the length of a rectangle in (3+√7) and it's with is (1+2√7). what is the area of the rectangle? what is the perimeter of the rectangle
Answers
Answer:
Area: (3+√7) x (1+2√7) = 17+7√7 = 35.52
Perimeter: 2(3+√7) + 2(1+2√7) = 8+6√7 = 23.87
What is one website you can visit in order to request free credit report from any of the three bureaus?
Answers
Answer: annualcreditreport.com
Step-by-step explanation: The only authorized website for free credit reports, or call 1-877-322-8228
Rationalize the denominator.
9-10/2
V2+1
Answers
Answer:
d. 19√2 -29
Step-by-step explanation:
Multiply numerator and denominator by the conjugate of the denominator.
[tex]\dfrac{9-10\sqrt{2}}{\sqrt{2}+1}=\dfrac{(9-10\sqrt{2})(\sqrt{2}-1)}{(\sqrt{2}+1)(\sqrt{2}-1)}\\\\=\dfrac{9\sqrt{2}-9-10\cdot2+10\sqrt{2}}{2-1}=\boxed{19\sqrt{2}-29}[/tex]
Answer:
Step-by-step explanation:
consider the system of equations. which shows an equivalent system of equations?
see attatched
Answers
Answer:
A.
Step-by-step explanation:
All choices show the first original equation.
Each choice shows a different second equation.
Take the second original equation:
6x + 5y = 30
Multiply both sides by -5.
-30x - 25y = -150
Answer: A.
PLS HELP WILL MARK BRAINLIEST
Answers
Hi guys im stuck on this maths question
(2/5)^-3
Answers
Answer:
15.625
Step-by-step explanation:
Answer:
[tex] (\frac{2}{5} ) {}^{ - 3} \\ = (\frac{a}{b} ) {}^{ - x} = (\frac{b}{a} ) {}^{x} \\ so \: \: \: \: \: \: (\frac{2}{5} ) {}^{ - 3} \\ = (\frac{5}{2} ) {}^{3} \\ = \frac{5 {}^{3} }{2 {}^{3} } \\ \: = \: \frac{125}{8} [/tex]
Is 5.12 times 10n =512
Answers
Answer:
it is D
Step-by-step explanation:
I have to show you, but if I do it don't on the paper
Hi, I got 8 points off on this problem, can you help me figure out what I did wrong?
Answers
Answer:
Possible errors: Triangle classification and definition.
Step-by-step explanation:
An isoceles triangle has at least two congruent sides of the same length.
Given the triangle that has two equal angles, and that you'll have to prove that the triangle also has two equal sides.
Using the Converse of Isoceles Triangle Theorem, where it states that if a triangle has two congruent angles < PQR ≅ < PRQ, for which opposite sides of those angles are congruent:
The opposite side of <PQR is line PR.The opposite side of <PRQ is line PQ.Additionally, connecting point P to point X along the line QR such that PX ⊥ QR, divides △PQR into two symmetrical sections, where points Q and R are equidistant from point X.
Answer:
Possible errors: Triangle classification and definition.
What is the equation for the line in slope-intercept form?
Answers
Hgfxdffggggujjcfccchhjbvg
find the slope from the pair of the points
(-3,-4) (1,5)
Answers
Answer:
2.25
Step-by-step explanation:
m = 9 / 4 = 2.25
points belong to an increasing, linear function.
Equation: y = 2.25x + 2.75.
BRAINLIEST?
Kim Barney pays a $290.00 annual premium for an insurance plan with a $500 deductible. The company pays 80% of the remaining expense. If Kim had $2,500.00 in medical expenses, calculate the following.
Answers
The amount that Kim Barney spends is $342 for medical expenses.
What is buying cost?Buying cost is the cost at which someone buys or is willing to buy shares, bonds.( including the tax)
here, we have,
Given that,
Kim Barney pays a $290.00 yearly premium for a $500.00 deductible insurance plan. 80 percent of the remaining cost is covered by the business. If Kim has medical costs of $2,500.00
To find : The amount that Kim barney spends for the medical expenses.
If the business covers 80% of the remaining balance ($1710), they will be responsible for paying $1368 of it.
10% of 1710 is 171
171x8=1368
The insurance provider covers the $1368.
Kim Barney spends $342.
Consequently, Kim Barney spends the following amount on medical costs $342.
To learn more about the cost click here:
brainly.com/question/30045916
#SPJ2
What is .7899 rounded 4 decimal places
Answers
Hope this helped. :)
Which expression represents 81 decreased by an unknown number?
81÷a
81a
81−a
81 + a
Answers
Answer:
81 - a
Step-by-step explanation:
Decreased
means to subtract
81 –
by an unknown number
means a variable such as a or x
therefor
81 – a
Hey everybody! Not a super hard question here! Anybody think they can help me out?
Identify the correct domain and range.
Answers
Answer
B, the second choice
Step-by-step explanation:
the domain is defined as all possible x values of a function and the range is defined as all possible y values, so the domain would be all real numbers since x can be any value, and the range cannot be more than 3, since y=3 is the vertex of the parabola.
có 100 công nhân sản xuất trong một ngày được 1200 đợn vị sản phẩm với tổng chi phí là 2400 USD
Answers
Answer:
4 better inbox
Step-by-step explanation:
Which sentence uses correct subject-verb agreement?
A. The river through our cities are polluted
B. Mountains in Colorado is beautiful.
C.The book about South American rivers is overdue.
D. The trees around our state is blooming.
Answers
Answer: C
Step-by-step explanation: the guy up top is correct:)
What is negative 10 divided by .22
Answers
Answer:
That would be negative 45 or - 45
Please correct me if im wrong
Two integers are relatively prime if, and only if, their greatest common divisor is 1. For example, 2 and 3 are relatively prime, 1 and 1 are relatively prime, but 2 and 2 are not. You toss two dice, one blue and one gray. What is the probability that when the dice stop rolling that the pip count on the blue die is relatively prime to the pip count on the gray die and the gray die is showing six pips
Answers
Answer:
A woman wants to measure the height of a nearby building. She places a 7 ft pole in the shadow of the building so that the shadow of the pole is exactly covered by the shadow of the building. The total length of the building's shadow is 184 ft, and the pole casts a shadow that is 5.5ft long. How tall is the building? Round your answer to the nearest foot. (The figure is not drawn to scale.)
Step-by-step explanation:
A woman wants to measure the height of a nearby building. She places a 7 ft pole in the shadow of the building so that the shadow of the pole is exactly covered by the shadow of the building. The total length of the building's shadow is 184 ft, and the pole casts a shadow that is 5.5ft long. How tall is the building? Round your answer to the nearest foot. (The figure is not drawn to scale.)A woman wants to measure the height of a nearby building. She places a 7 ft pole in the shadow of the building so that the shadow of the pole is exactly covered by the shadow of the building. The total length of the building's shadow is 184 ft, and the pole casts a shadow that is 5.5ft long. How tall is the building? Round your answer to the nearest foot. (The figure is not drawn to scale.)A woman wants to measure the height of a nearby building. She places a 7 ft pole in the shadow of the building so that the shadow of the pole is exactly covered by the shadow of the building. The total length of the building's shadow is 184 ft, and the pole casts a shadow that is 5.5ft long. How tall is the building? Round your answer to the nearest foot. (The figure is not drawn to scale.)
Henry is investing at a continuously compounded annual interest rate of 4.4%. How many years will it take for the balance to triple? Round your answer up to the nearest whole number, and do not include units in your answer.
Answers
The number of years it would take the amount to triple is 25 years.
The formula that would be used to determine the number of years it would take the balance to triple is:
FV = PV x [tex]e^{r}[/tex]N
Where:
n = number of years fv = future value PV = present value e = 2.7182818 r = interest rate3 = [tex]e^{0.044}[/tex]N
Take the log of both sides
log(3) / log(e) / (0.044) = 25 years
A similar question was answered here: https://brainly.com/question/7133042
