Consider the following integral.

${\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}\frac{x^6}{(2+x^7{)}^4}dx$

Find a change of variables to rewrite the integrand as $\frac{1}{7u^4}du.$

$u=$

$du=$

Evaluate the given integral. $($Remember the constant of integration.$)$