### Home > CALC > Chapter 7 > Lesson 7.2.3 > Problem 7-90

7-90.

To make this easier, factor the 6 out of the limit.

The 6 will be factored out of the integral as well.

We will now write all *n*-terms as *x*-terms.

Find *dx*:

Find the integrand:*x* is a variable. So find the part of the sum that changes:

So the integrand must be *f*(*x*) = *x* + 3.

Find the bounds:

Look at the original sum.