Question

In ∫ 2x(x^(2)+3)dx, if we let u=x^(2)+3,then
1.the integral form is u^(n)du and du=2x
2.the integral form u^(n)du cannot be used because n=1
3.the integral form is u^(n)du and du=2dx
4.the integral form is u^(n)du and du=2xdx

Answer 1

du/dx=2x
du=(2x)dx, integral becoms udu