12,5x^2-60x-12,5=0

Solution for 12,5x^2-60x-12,5=0 equation:

12.5x^2-60x-12.5=0

a = 12.5; b = -60; c = -12.5;
Δ = b2-4ac
Δ = -602-4·12.5·(-12.5)
Δ = 4225
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{4225}=65$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-60)-65}{2*12.5}=\frac{-5}{25}
=-1/5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-60)+65}{2*12.5}=\frac{125}{25}
=5
$