y*y-20y+64=0

Solution for y*y-20y+64=0 equation:

y*y-20y+64=0

We add all the numbers together, and all the variables

-20y+y*y+64=0

Wy multiply elements

y^2-20y+64=0

a = 1; b = -20; c = +64;
Δ = b2-4ac
Δ = -202-4·1·64
Δ = 144
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{144}=12$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-20)-12}{2*1}=\frac{8}{2}
=4
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-20)+12}{2*1}=\frac{32}{2}
=16
$