20=(2x+1)(2x)

Solution for 20=(2x+1)(2x) equation:

20=(2x+1)(2x)

We move all terms to the left:

20-((2x+1)(2x))=0


We calculate terms in parentheses: -((2x+1)2x), so:

(2x+1)2x

We multiply parentheses

4x^2+2x

Back to the equation:

-(4x^2+2x)


We get rid of parentheses

-4x^2-2x+20=0

a = -4; b = -2; c = +20;
Δ = b2-4ac
Δ = -22-4·(-4)·20
Δ = 324
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{324}=18$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-2)-18}{2*-4}=\frac{-16}{-8}
=+2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-2)+18}{2*-4}=\frac{20}{-8}
=-2+1/2
$