Hello,Originally Posted bycinder

to 1.:

use u(x) = 2x+3. Then du/dx = 2. That means du = 2*dx.

So you could use the substitution method if there are the factor 2:

Now you can re-substitute and you'll get:

to 2.:

Factorize (x^2-1) = (x+1)(x-1). Then you can cancel (x-1) and you'll get:

.

From here on you know what to do!

Greetings

EB