Find the integral by substitution

Question

∫ [(16 x3)/(x4 + 5)] dx

∫[ 4 x/(√{x2 + 3})] dx

∫ 8 x2 e4 x3 +7 dx

PLEASE help with all three. i'd really appreciate it

Answer 1

Hints:
1. if u=x⁴+5
du/dx
=d(x⁴+5)/dx
=4x³
or du = 4x³ dx

2. u=√{x² + 3}
du/dx = x/√{x² + 3}
du = xdx/√{x² + 3}

3. u=?
8x²e⁴/(x³ +7)