X2+20x+56=0

Solution for X2+20x+56=0 equation:

X2+20X+56=0

We add all the numbers together, and all the variables

X^2+20X+56=0

a = 1; b = 20; c = +56;
Δ = b2-4ac
Δ = 202-4·1·56
Δ = 176
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:

$\sqrt{\Delta}=\sqrt{176}=\sqrt{16*11}=\sqrt{16}*\sqrt{11}=4\sqrt{11}$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(20)-4\sqrt{11}}{2*1}=\frac{-20-4\sqrt{11}}{2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(20)+4\sqrt{11}}{2*1}=\frac{-20+4\sqrt{11}}{2}
$