Primitive of Reciprocal of Root of a x squared plus b x plus c/a equal to 0

Theorem
For $a x^2 + b x + c > 0$:
 * $\ds \int \frac {\d x} {\sqrt {a x^2 + b x + c} } = \frac {2 \sqrt {b x + c} } b + C$

when $a = 0$.