Find the integral of √x2+a2 with respect to x and evaluate ∫√16x2+25 dx.
∫√x2+a2=x2√x2+a2+a22log(x+√x2+a2) + c for the derivation
I = ∫√16x2+25 dx
= ∫√(4x)2+(5)2 dx
= [4x2√16x2+25+252log∣∣4x+√16x2+25∣∣]+c