x2-28x-128=0

Solution for x2-28x-128=0 equation:

x2-28x-128=0

We add all the numbers together, and all the variables

x^2-28x-128=0

a = 1; b = -28; c = -128;
Δ = b2-4ac
Δ = -282-4·1·(-128)
Δ = 1296
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1296}=36$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-28)-36}{2*1}=\frac{-8}{2}
=-4
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-28)+36}{2*1}=\frac{64}{2}
=32
$