4x(2x-1)=20

Solution for 4x(2x-1)=20 equation:

4x(2x-1)=20

We move all terms to the left:

4x(2x-1)-(20)=0

We multiply parentheses

8x^2-4x-20=0

a = 8; b = -4; c = -20;
Δ = b2-4ac
Δ = -42-4·8·(-20)
Δ = 656
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{656}=\sqrt{16*41}=\sqrt{16}*\sqrt{41}=4\sqrt{41}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-4)-4\sqrt{41}}{2*8}=\frac{4-4\sqrt{41}}{16}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-4)+4\sqrt{41}}{2*8}=\frac{4+4\sqrt{41}}{16}
$