1. ## Evaluate integrals

A)integral,top limit =1, bottom limit = -infinity 1/1+x^2dx

B)integral,top limit =infinity, bottom limit = 0 te^-t dt

Evaluate the given improper integral or show that it diverges

2. ## Re: Evaluate integrals

So
A) $\int_{-\infty}^1 \frac{1}{1+ x^2} dx$

B) $\int_0^\infty t e^{-t}dt$

Okay, now what is your difficulty? The first can be found in any table of integrals- $\frac{1}{1+ x^2}$ is the direct derivative of a function. For (B), use integration by parts with u= t, $dv=e^{-t}dt$.