(20-2x)(30-2x)=375

Solution for (20-2x)(30-2x)=375 equation:

(20-2x)(30-2x)=375

We move all terms to the left:

(20-2x)(30-2x)-(375)=0

We add all the numbers together, and all the variables

(-2x+20)(-2x+30)-375=0

We multiply parentheses ..

(+4x^2-60x-40x+600)-375=0

We get rid of parentheses

4x^2-60x-40x+600-375=0

We add all the numbers together, and all the variables

4x^2-100x+225=0

a = 4; b = -100; c = +225;
Δ = b2-4ac
Δ = -1002-4·4·225
Δ = 6400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{6400}=80$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-100)-80}{2*4}=\frac{20}{8}
=2+1/2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-100)+80}{2*4}=\frac{180}{8}
=22+1/2
$