5y^2-60y-225=0

Solution for 5y^2-60y-225=0 equation:

5y^2-60y-225=0

a = 5; b = -60; c = -225;
Δ = b2-4ac
Δ = -602-4·5·(-225)
Δ = 8100
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{8100}=90$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-60)-90}{2*5}=\frac{-30}{10}
=-3
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-60)+90}{2*5}=\frac{150}{10}
=15
$