# How do you factor completely 3a^2+12a-15?

Jun 10, 2016

$y = 3 {a}^{2} + 12 a - 15$
One real roots is $\frac{c}{a} = - \frac{15}{3}$, and the factor is $\left(x + \frac{15}{3}\right)$
$y = \left(x - 1\right) \left(x + \frac{15}{3}\right) = \left(x - 1\right) \left(3 x + 15\right)$