-5x^2-25x+120=0

Solution for -5x^2-25x+120=0 equation:

-5x^2-25x+120=0

a = -5; b = -25; c = +120;
Δ = b2-4ac
Δ = -252-4·(-5)·120
Δ = 3025
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{3025}=55$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-25)-55}{2*-5}=\frac{-30}{-10}
=+3
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-25)+55}{2*-5}=\frac{80}{-10}
=-8
$