(50-2x)(40-2x)=2000

Solution for (50-2x)(40-2x)=2000 equation:

(50-2x)(40-2x)=2000

We move all terms to the left:

(50-2x)(40-2x)-(2000)=0

We add all the numbers together, and all the variables

(-2x+50)(-2x+40)-2000=0

We multiply parentheses ..

(+4x^2-80x-100x+2000)-2000=0

We get rid of parentheses

4x^2-80x-100x+2000-2000=0

We add all the numbers together, and all the variables

4x^2-180x=0

a = 4; b = -180; c = 0;
Δ = b2-4ac
Δ = -1802-4·4·0
Δ = 32400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{32400}=180$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-180)-180}{2*4}=\frac{0}{8}
=0
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-180)+180}{2*4}=\frac{360}{8}
=45
$