(9x-1)(4x+4)=0

Solution for (9x-1)(4x+4)=0 equation:

(9x-1)(4x+4)=0

We multiply parentheses ..

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

We get rid of parentheses

36x^2+36x-4x-4=0

We add all the numbers together, and all the variables

36x^2+32x-4=0

a = 36; b = 32; c = -4;
Δ = b2-4ac
Δ = 322-4·36·(-4)
Δ = 1600
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1600}=40$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(32)-40}{2*36}=\frac{-72}{72}
=-1
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(32)+40}{2*36}=\frac{8}{72}
=1/9
$