9(5-x)(x+2)=0

Solution for 9(5-x)(x+2)=0 equation:

9(5-x)(x+2)=0

We add all the numbers together, and all the variables

9(-1x+5)(x+2)=0

We multiply parentheses ..

9(-1x^2-2x+5x+10)=0

We multiply parentheses

-9x^2-18x+45x+90=0

We add all the numbers together, and all the variables

-9x^2+27x+90=0

a = -9; b = 27; c = +90;
Δ = b2-4ac
Δ = 272-4·(-9)·90
Δ = 3969
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{3969}=63$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(27)-63}{2*-9}=\frac{-90}{-18}
=+5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(27)+63}{2*-9}=\frac{36}{-18}
=-2
$