Evaluate the integral using u substitution

Evaluate the following indefinite integral

$\displaystyle\int{3x^6} dx$

Evaluate the indefinite integral

$\displaystyle\int 7\sqrt{x}\ dx$

Find the following indefinite integral

$\displaystyle\int 3x^6 + 5 + 7\sqrt{x}\ dx$

Find the antiderivative of $x^3$