4(x^2+15x)=216

Solution for 4(x^2+15x)=216 equation:

4(x^2+15x)=216

We move all terms to the left:

4(x^2+15x)-(216)=0

We multiply parentheses

4x^2+60x-216=0

a = 4; b = 60; c = -216;
Δ = b2-4ac
Δ = 602-4·4·(-216)
Δ = 7056
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{7056}=84$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(60)-84}{2*4}=\frac{-144}{8}
=-18
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(60)+84}{2*4}=\frac{24}{8}
=3
$