2y(2y+5)=0

Solution for 2y(2y+5)=0 equation:

2y(2y+5)=0

We multiply parentheses

4y^2+10y=0

a = 4; b = 10; c = 0;
Δ = b2-4ac
Δ = 102-4·4·0
Δ = 100
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{100}=10$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(10)-10}{2*4}=\frac{-20}{8}
=-2+1/2
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(10)+10}{2*4}=\frac{0}{8}
=0
$