4y(y-8)=-20

Solution for 4y(y-8)=-20 equation:

4y(y-8)=-20

We move all terms to the left:

4y(y-8)-(-20)=0

We add all the numbers together, and all the variables

4y(y-8)+20=0

We multiply parentheses

4y^2-32y+20=0

a = 4; b = -32; c = +20;
Δ = b2-4ac
Δ = -322-4·4·20
Δ = 704
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{704}=\sqrt{64*11}=\sqrt{64}*\sqrt{11}=8\sqrt{11}$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-32)-8\sqrt{11}}{2*4}=\frac{32-8\sqrt{11}}{8}
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-32)+8\sqrt{11}}{2*4}=\frac{32+8\sqrt{11}}{8}
$