(x*x)-x=18

Solution for (x*x)-x=18 equation:

(x*x)-x=18

We move all terms to the left:

(x*x)-x-(18)=0

We add all the numbers together, and all the variables

(+x*x)-x-18=0

We add all the numbers together, and all the variables

-1x+(+x*x)-18=0

We get rid of parentheses

-1x+x*x-18=0

Wy multiply elements

x^2-1x-18=0

a = 1; b = -1; c = -18;
Δ = b2-4ac
Δ = -12-4·1·(-18)
Δ = 73
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{73}}{2*1}=\frac{1-\sqrt{73}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-1)+\sqrt{73}}{2*1}=\frac{1+\sqrt{73}}{2}
$