(2x-9)*(-x-2)=0

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

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

We add all the numbers together, and all the variables

(2x-9)(-1x-2)=0

We multiply parentheses ..

(-2x^2-4x+9x+18)=0

We get rid of parentheses

-2x^2-4x+9x+18=0

We add all the numbers together, and all the variables

-2x^2+5x+18=0

a = -2; b = 5; c = +18;
Δ = b2-4ac
Δ = 52-4·(-2)·18
Δ = 169
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{169}=13$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(5)-13}{2*-2}=\frac{-18}{-4}
=4+1/2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(5)+13}{2*-2}=\frac{8}{-4}
=-2
$