(12+8)-4x2=x

Solution for (12+8)-4x2=x equation:

(12+8)-4x^2=x

We move all terms to the left:

(12+8)-4x^2-(x)=0

We add all the numbers together, and all the variables

-4x^2-x+20=0

We add all the numbers together, and all the variables

-4x^2-1x+20=0

a = -4; b = -1; c = +20;
Δ = b2-4ac
Δ = -12-4·(-4)·20
Δ = 321
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-1)-\sqrt{321}}{2*-4}=\frac{1-\sqrt{321}}{-8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-1)+\sqrt{321}}{2*-4}=\frac{1+\sqrt{321}}{-8}
$