y^2-8y-16+4=0

Solution for y^2-8y-16+4=0 equation:

y^2-8y-16+4=0

We add all the numbers together, and all the variables

y^2-8y-12=0

a = 1; b = -8; c = -12;
Δ = b2-4ac
Δ = -82-4·1·(-12)
Δ = 112
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:

$\sqrt{\Delta}=\sqrt{112}=\sqrt{16*7}=\sqrt{16}*\sqrt{7}=4\sqrt{7}$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-8)-4\sqrt{7}}{2*1}=\frac{8-4\sqrt{7}}{2}
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-8)+4\sqrt{7}}{2*1}=\frac{8+4\sqrt{7}}{2}
$