y^2+64y-64=0

Solution for y^2+64y-64=0 equation:

y^2+64y-64=0

a = 1; b = 64; c = -64;
Δ = b2-4ac
Δ = 642-4·1·(-64)
Δ = 4352
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:

$\sqrt{\Delta}=\sqrt{4352}=\sqrt{256*17}=\sqrt{256}*\sqrt{17}=16\sqrt{17}$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(64)-16\sqrt{17}}{2*1}=\frac{-64-16\sqrt{17}}{2}
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(64)+16\sqrt{17}}{2*1}=\frac{-64+16\sqrt{17}}{2}
$