### Home > APCALC > Chapter 7 > Lesson 7.3.4 > Problem7-144

7-144.

Rewrite each integral using a $u$‑substitution. Pay attention to the bounds. You do not need to complete the integration.

1. $\int _ { 0 } ^ { 2 } x e ^ { 3 x ^ { 2 } } d x$

Let $u = 3x^2$. Write a new integrand AND write new bounds.

$=\frac{1}{6}\int_{0}^{12}e^{u}du$

1. $\int _ { - 2 } ^ { 3 } \frac { 5 x ^ { 2 } } { x ^ { 3 } + 1 } d x$

Remember that the current bounds are $x$-values. They need to be converted to $u$-values.