-20x-25=-4x^2

Solution for -20x-25=-4x^2 equation:

-20x-25=-4x^2

We move all terms to the left:

-20x-25-(-4x^2)=0

We get rid of parentheses

4x^2-20x-25=0

a = 4; b = -20; c = -25;
Δ = b2-4ac
Δ = -202-4·4·(-25)
Δ = 800
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:

$\sqrt{\Delta}=\sqrt{800}=\sqrt{400*2}=\sqrt{400}*\sqrt{2}=20\sqrt{2}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-20)-20\sqrt{2}}{2*4}=\frac{20-20\sqrt{2}}{8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-20)+20\sqrt{2}}{2*4}=\frac{20+20\sqrt{2}}{8}
$