Find the derivative of f(x)=ln(x+x2+a2)f(x) = \ln\left(x + \sqrt{x^2 + a^2}\right)f(x)=ln(x+x2+a2) with respect to xxx.
1x2+a2\frac{1}{\sqrt{x^2 + a^2}}x2+a21
1x+x2+a2\frac{1}{x + \sqrt{x^2 + a^2}}x+x2+a21
xx2+a2\frac{x}{\sqrt{x^2 + a^2}}x2+a2x
1x2+a2\frac{1}{x^2 + a^2}x2+a21