Find the derivative of f(x)=x2+1f(x) = \sqrt{x^2+1}f(x)=x2+1.
xx2+1\frac{x}{\sqrt{x^2+1}}x2+1x
12x2+1\frac{1}{2\sqrt{x^2+1}}2x2+11
2xx2+1\frac{2x}{\sqrt{x^2+1}}x2+12x
2x\sqrt{2x}2x