128=(18-x)*(12-2x)

Solution for 128=(18-x)*(12-2x) equation:

128=(18-x)(12-2x)

We move all terms to the left:

128-((18-x)(12-2x))=0

We add all the numbers together, and all the variables

-((-1x+18)(-2x+12))+128=0

We multiply parentheses ..

-((+2x^2-12x-36x+216))+128=0


We calculate terms in parentheses: -((+2x^2-12x-36x+216)), so:

(+2x^2-12x-36x+216)

We get rid of parentheses

2x^2-12x-36x+216

We add all the numbers together, and all the variables

2x^2-48x+216

Back to the equation:

-(2x^2-48x+216)


We get rid of parentheses

-2x^2+48x-216+128=0

We add all the numbers together, and all the variables

-2x^2+48x-88=0

a = -2; b = 48; c = -88;
Δ = b2-4ac
Δ = 482-4·(-2)·(-88)
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{-(48)-40}{2*-2}=\frac{-88}{-4}
=+22
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(48)+40}{2*-2}=\frac{-8}{-4}
=+2
$