x^2+20x+72=0

Solution for x^2+20x+72=0 equation:

x^2+20x+72=0

a = 1; b = 20; c = +72;
Δ = b2-4ac
Δ = 202-4·1·72
Δ = 112
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:

$\sqrt{\Delta}=\sqrt{112}=\sqrt{16*7}=\sqrt{16}*\sqrt{7}=4\sqrt{7}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(20)-4\sqrt{7}}{2*1}=\frac{-20-4\sqrt{7}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(20)+4\sqrt{7}}{2*1}=\frac{-20+4\sqrt{7}}{2}
$