0=9(x-9)(x+4)

Solution for 0=9(x-9)(x+4) equation:

0=9(x-9)(x+4)

We move all terms to the left:

0-(9(x-9)(x+4))=0

We add all the numbers together, and all the variables

-(9(x-9)(x+4))=0

We multiply parentheses ..

-(9(+x^2+4x-9x-36))=0


We calculate terms in parentheses: -(9(+x^2+4x-9x-36)), so:

9(+x^2+4x-9x-36)

We multiply parentheses

9x^2+36x-81x-324

We add all the numbers together, and all the variables

9x^2-45x-324

Back to the equation:

-(9x^2-45x-324)


We get rid of parentheses

-9x^2+45x+324=0

a = -9; b = 45; c = +324;
Δ = b2-4ac
Δ = 452-4·(-9)·324
Δ = 13689
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{13689}=117$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(45)-117}{2*-9}=\frac{-162}{-18}
=+9
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(45)+117}{2*-9}=\frac{72}{-18}
=-4
$