(40-2x)(36-2x)-1440=0

Solution for (40-2x)(36-2x)-1440=0 equation:

(40-2x)(36-2x)-1440=0

We add all the numbers together, and all the variables

(-2x+40)(-2x+36)-1440=0

We multiply parentheses ..

(+4x^2-72x-80x+1440)-1440=0

We get rid of parentheses

4x^2-72x-80x+1440-1440=0

We add all the numbers together, and all the variables

4x^2-152x=0

a = 4; b = -152; c = 0;
Δ = b2-4ac
Δ = -1522-4·4·0
Δ = 23104
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{23104}=152$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-152)-152}{2*4}=\frac{0}{8}
=0
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-152)+152}{2*4}=\frac{304}{8}
=38
$