Primitive of Reciprocal of Root of a x squared plus b x plus c/a greater than 0/Zero Discriminant

Theorem
Let $a \in \R_{>0}$.

Let $b^2 - 4 a c = 0$.

Then for $x \in \R$ such that $a x^2 + b x + c > 0$:


 * $\ds \int \frac {\d x} {\sqrt {a x^2 + b x + c} } = \frac 1 {\sqrt a} \ln \size {2 a x + b} + C$

Proof
Let $b^2 - 4 a c = 0$.

Then: