-5x2-40x+525=0

Solution for -5x2-40x+525=0 equation:

-5x^2-40x+525=0

a = -5; b = -40; c = +525;
Δ = b2-4ac
Δ = -402-4·(-5)·525
Δ = 12100
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{12100}=110$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-40)-110}{2*-5}=\frac{-70}{-10}
=+7
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-40)+110}{2*-5}=\frac{150}{-10}
=-15
$