integral of $(x^2)^n$

Question

I tried two methods of doing this,

a. $\int(x^2)^ndx = \int{x^{2n}}dx = \frac {x^{2n+1}}{2n+1}+C$

b. $\int(x^2)^ndx = \frac{({x^2})^{n+1}}{(n+1)(2x)}+C = \frac {x^{2n+1}}{2n+2}+C$

why is it different?