134k views
1 vote
Consider the second order linear equation.

y" - 8y' + 16y = 0.
Find its general solution.

User Rkrzr
by
8.0k points

1 Answer

5 votes

the general solution of the equation y" - 8y' + 16y = 0 is

y = ye^4x - 2y₀xe^4x.

The general solution of the second order linear equation y" - 8y' + 16y = 0 is

y = C₁e^4x + C₂e²x,

where C₁ and C₂ are arbitrary constants.

We can find this solution by assuming that the solution is of the form y = e^(rx). Substituting this into the equation, we get

r²e^(rx) - 8re^(rx) + 16e^(rx) = 0.

Dividing both sides by e^(rx), we get

r² - 8r + 16 = 0.

Factoring this equation, we get

(r - 4)² = 0.

Therefore, r = 4 is a double root of the equation.

This means that the general solution of the equation is of the form y = (C₁ + C₂x)e^4x, where C₁ and C₂ are arbitrary constants.

To find the constants C₁ and C₂, we can use the fact that the solution must also satisfy the initial conditions y(0) = y₀ and y'(0) = y₁.

Substituting y = (C₁ + C₂x)e^4x into y(0) = y₀, we get

y₀ = (C₁ + 0)e^4·0 = C₁.

Substituting y = (C₁ + C₂x)e^4x into y'(0) = y₁, we get

y₁ = (4C₁ + C₂)e^4·0 = 4C₁.

Solving for C₁, we get C₁ = y₀. Substituting this into y = (C₁ + C₂x)e^4x, we get

y = (y₀ + C₂x)e^4x.

To find C₂, we can differentiate this equation, to find y'.

y' = (C₂ + 4y₀x)e^4x.

Substituting y = (y₀ + C₂x)e^4x and y' = (C₂ + 4y₀x)e^4x into y'' = 8y' - 16y, we get

e^4x(y₀ + C₂x)'' = 8e^4x(C₂ + 4y₀x) - 16e^4x(y₀ + C₂x).

Simplifying this equation, we get

C₂ = -2y₀.

User Qiaosen Huang
by
8.4k points

No related questions found

Welcome to QAmmunity.org, where you can ask questions and receive answers from other members of our community.

9.4m questions

12.2m answers

Categories