x2-20x-136=0

Solution for x2-20x-136=0 equation:

x2-20x-136=0

We add all the numbers together, and all the variables

x^2-20x-136=0

a = 1; b = -20; c = -136;
Δ = b2-4ac
Δ = -202-4·1·(-136)
Δ = 944
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:

$\sqrt{\Delta}=\sqrt{944}=\sqrt{16*59}=\sqrt{16}*\sqrt{59}=4\sqrt{59}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-20)-4\sqrt{59}}{2*1}=\frac{20-4\sqrt{59}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-20)+4\sqrt{59}}{2*1}=\frac{20+4\sqrt{59}}{2}
$