3x2+15x=108

Solution for 3x2+15x=108 equation:

3x^2+15x=108

We move all terms to the left:

3x^2+15x-(108)=0

a = 3; b = 15; c = -108;
Δ = b2-4ac
Δ = 152-4·3·(-108)
Δ = 1521
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1521}=39$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(15)-39}{2*3}=\frac{-54}{6}
=-9
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(15)+39}{2*3}=\frac{24}{6}
=4
$