(x-11)(2x+9)=0

Solution for (x-11)(2x+9)=0 equation:

(x-11)(2x+9)=0

We multiply parentheses ..

(+2x^2+9x-22x-99)=0

We get rid of parentheses

2x^2+9x-22x-99=0

We add all the numbers together, and all the variables

2x^2-13x-99=0

a = 2; b = -13; c = -99;
Δ = b2-4ac
Δ = -132-4·2·(-99)
Δ = 961
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{961}=31$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-13)-31}{2*2}=\frac{-18}{4}
=-4+1/2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-13)+31}{2*2}=\frac{44}{4}
=11
$