y(y-31)=0

Solution for y(y-31)=0 equation:

y(y-31)=0

We multiply parentheses

y^2-31y=0

a = 1; b = -31; c = 0;
Δ = b2-4ac
Δ = -312-4·1·0
Δ = 961
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{961}=31$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-31)-31}{2*1}=\frac{0}{2}
=0
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-31)+31}{2*1}=\frac{62}{2}
=31
$