(20x-x)x=36

Solution for (20x-x)x=36 equation:

(20x-x)x=36

We move all terms to the left:

(20x-x)x-(36)=0

We add all the numbers together, and all the variables

(+19x)x-36=0

We multiply parentheses

19x^2-36=0

a = 19; b = 0; c = -36;
Δ = b2-4ac
Δ = 02-4·19·(-36)
Δ = 2736
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:

$\sqrt{\Delta}=\sqrt{2736}=\sqrt{144*19}=\sqrt{144}*\sqrt{19}=12\sqrt{19}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-12\sqrt{19}}{2*19}=\frac{0-12\sqrt{19}}{38}
=-\frac{12\sqrt{19}}{38}
=-\frac{6\sqrt{19}}{19}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+12\sqrt{19}}{2*19}=\frac{0+12\sqrt{19}}{38}
=\frac{12\sqrt{19}}{38}
=\frac{6\sqrt{19}}{19}
$