4x^2-8x=396

Solution for 4x^2-8x=396 equation:

4x^2-8x=396

We move all terms to the left:

4x^2-8x-(396)=0

a = 4; b = -8; c = -396;
Δ = b2-4ac
Δ = -82-4·4·(-396)
Δ = 6400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{6400}=80$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-8)-80}{2*4}=\frac{-72}{8}
=-9
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-8)+80}{2*4}=\frac{88}{8}
=11
$