write
x^2 + 2x + 3 as
m ( x^2 + x + 1) + n \frac{d\left(x^2 + x + 1 \right)}{dx} + u
evaluate m , n, u
u get
m = 1
n=1/2
u = 3/2
integral reduces as
{\color{blue} \int\left[ \left(x^2 + x +1 \right) + \frac{1}{2} ( 2x + 1) + \frac{3}{2}\right]\sqrt{x^2 + x +1} . dx }
convert these into perfect squares and use formula for
now use the formula
{\color{blue} \int \sqrt{x^2 + a^2} . dx }
and done