Evaluate the integral $by$ completing the square and using trigonometric substitution.

${\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}\frac{dx}{\sqrt[\phantom{2}]{?}3+x-x^2}C$ for the arbitrary constant. Absorb

into $Cas$ much $as$ possible.${\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}\frac{dx}{\sqrt[\phantom{2}]{?}3+x-x^2}$