Substitution Rule for Indefinite Integrals

[temaire]

Homework Statement

\int2e^-^7^xdx

Homework Equations

None

The Attempt at a Solution

(\frac{-2}{7})(\frac{e^-^7^x}{-7})+C


This is as far as I can go, but the answer is:

\frac{-2e^-^7^x}{7}+C

 

[rocomath]

How did you get two 1/7 terms?

 

[temaire]

I took the antiderivative of e^-^7^x.

 

[rocomath]

I took the antiderivative of e^-^7^x.

So, why do you have 1/7 * 1/7? Just do it again from scratch and you'll probably see what you did wrong.

 

[rocomath]

2\int e^{-7x}dx

-\frac 2 7\int -7e^{-7x}dx

You don't need to divide by another -7. It's already in standard form!

 

[temaire]

I've got it now, thanks.