# Calculate the integral

1. Feb 1, 2009

### intenzxboi

1. The problem statement, all variables and given/known data

$$\int$$(sin (e^(-2x))) / e^(2x)

3. The attempt at a solution

so i set
u=e^2x
du=(e^2x)(2) dx

im kinda stuck on how to get rid of the e^-2x

2. Feb 1, 2009

### arildno

Therefore, du/dx=-2u, that is dx=-du/2u

Use this to simplify your integrand!

3. Feb 1, 2009

### intenzxboi

k using u=e^-2x
du=-2 (e^-2x) dx

so...

-1/2 $$\int$$ sin u du

-1/2 (-cos u) + c is that right???

4. Feb 1, 2009

### Dick

Sure. But there is a simpler way to write (-1/2)*(-cos(u)).

5. Feb 1, 2009

### intenzxboi

so final answer is cos u /2

6. Feb 1, 2009

### Dick

cos(u)/2+C. Use more parentheses. cos u /2 can also be read cos(u/2).