54=-2x+x^2-x

Solution for 54=-2x+x^2-x equation:

54=-2x+x^2-x

We move all terms to the left:

54-(-2x+x^2-x)=0

We get rid of parentheses

-x^2+2x+x+54=0

We add all the numbers together, and all the variables

-1x^2+3x+54=0

a = -1; b = 3; c = +54;
Δ = b2-4ac
Δ = 32-4·(-1)·54
Δ = 225
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{225}=15$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(3)-15}{2*-1}=\frac{-18}{-2}
=+9
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(3)+15}{2*-1}=\frac{12}{-2}
=-6
$