Question

Given: y" - 2y' = 6t + 5e^2t. Find the correct form to use for y_p if the equation is solved using Undetermined coefficients. Do NOT Solve the equation

Answer 1

Answer:

$y_p=A+Bt+Ce^{2t}$

Step-by-step explanation:

Given: $y'' - 2y' = 6t + 5e^{2t}$.

we need to find the correct form for $y_p$ if the equation is solve using undetermined coefficients.

A first order differential equation $\frac{\mathrm{d} y}{\mathrm{d} x}=f\left ( x,y \right )$ is said to be homogeneous if $f(tx,ty)=f(x,y)$ for all t.

Consider homogeneous equation $y''-2y'=0$

Let $y=e^{rt}$ be the solution .

We get $(r^2-2r)e^{rt}=0$

Since $e^{rt}\neq 0$, $r^2-2r=0$.

So, we get solution as $y_c=c_1+c_2e^{2t}$

As constant term and $e^{2t}$ are already in the R.H.S of equation

$y" - 2y' = 6t + 5e^{2t}$, we can take $y_p$ as $y_p=A+Bt+Ce^{2t}$