8x^2-20x=400

Solution for 8x^2-20x=400 equation:

8x^2-20x=400

We move all terms to the left:

8x^2-20x-(400)=0

a = 8; b = -20; c = -400;
Δ = b2-4ac
Δ = -202-4·8·(-400)
Δ = 13200
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{13200}=\sqrt{400*33}=\sqrt{400}*\sqrt{33}=20\sqrt{33}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-20)-20\sqrt{33}}{2*8}=\frac{20-20\sqrt{33}}{16}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-20)+20\sqrt{33}}{2*8}=\frac{20+20\sqrt{33}}{16}
$