-x^2-9x+136=0

Solution for -x^2-9x+136=0 equation:

-x^2-9x+136=0

We add all the numbers together, and all the variables

-1x^2-9x+136=0

a = -1; b = -9; c = +136;
Δ = b2-4ac
Δ = -92-4·(-1)·136
Δ = 625
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{625}=25$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-9)-25}{2*-1}=\frac{-16}{-2}
=+8
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-9)+25}{2*-1}=\frac{34}{-2}
=-17
$