Question

The family of functions y = ce^{-2x} + e^{-x} is solution of the equation y' + 2y = e^{-x}. Find the constant c which defines the solution which also satisfies the initial condition y(3)= 3.

Answer 1

Answer:

$c = 1190.2$

Step-by-step explanation:

We have the following solution:

$y(x) = ce^{-2x} + e^{-x}$

We want to find the value of x that satisfies the following condition:

y(3) = 3.

This means that when x = 3, y = 3. So

$y(x) = ce^{-2x} + e^{-x}$

$y(3) = ce^{-2*3} + e^{-3}$

$3 = ce^{-6} + e^{-3}$

$3 = ce^{-6} + 0.0498$

$ce^{-6} = 2.9502$

$c = \frac{2.9502}{e^{-6}}$

$c = 1190.2$