3x^2+90x-120=0

Solution for 3x^2+90x-120=0 equation:

3x^2+90x-120=0

a = 3; b = 90; c = -120;
Δ = b2-4ac
Δ = 902-4·3·(-120)
Δ = 9540
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{9540}=\sqrt{36*265}=\sqrt{36}*\sqrt{265}=6\sqrt{265}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(90)-6\sqrt{265}}{2*3}=\frac{-90-6\sqrt{265}}{6}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(90)+6\sqrt{265}}{2*3}=\frac{-90+6\sqrt{265}}{6}
$