Q:

Find a solution to y'(t) = te^-t satisfying the condition y(1) = 1.

Accepted Solution

A:
Answer:[tex]y=-e^{-t}(t+1)+1+\frac{2}{e}[/tex]Step-by-step explanation:The given differential equation is[tex]y'(t)=te^{-t}[/tex]It can be written as[tex]\frac{dy}{dt}=te^{-t}[/tex][tex]dy=te^{-t}dt[/tex]Integrate both sides.[tex]\int dy=\int te^{-t}dt[/tex]Apply ILATE rule on right side. Here, t is first function and [tex]e^{-t}[/tex] is the second function.[tex]y=t\int e^{-t}-\int (\frac{d}{dt}t\int e^{-t})[/tex][tex]y=-te^{-t}-\int (1\times (-e^{-t}))[/tex]         [tex]\int e^{-x}=-e^{-x}+C[/tex][tex]y=-te^{-t}+\int e^{-t}[/tex][tex]y=-te^{-t}-e^{-t}+C[/tex]             .... (1)Initial condition is y(1) = 1. It means at t=1 the value of y is 1.[tex]1=-(1)e^{-t}-e^{-(1)}+C[/tex] [tex]1=-e^{-1}-e^{-1}+C[/tex][tex]1=-2e^{-1}+C[/tex][tex]1=-\frac{2}{e}+C[/tex]Add [tex]\frac{2}{e}[/tex] on both sides.[tex]1+\frac{2}{e}=C[/tex]Substitute the value of C in equation (1).[tex]y=-te^{-t}-e^{-t}+1+\frac{2}{e}[/tex][tex]y=-e^{-t}(t+1)+1+\frac{2}{e}[/tex]Therefore, the solution of given initial value problem is [tex]y=-e^{-t}(t+1)+1+\frac{2}{e}[/tex].