18=x2-15x+2

Solution for 18=x2-15x+2 equation:

18=x2-15x+2

We move all terms to the left:

18-(x2-15x+2)=0

We add all the numbers together, and all the variables

-(+x^2-15x+2)+18=0

We get rid of parentheses

-x^2+15x-2+18=0

We add all the numbers together, and all the variables

-1x^2+15x+16=0

a = -1; b = 15; c = +16;
Δ = b2-4ac
Δ = 152-4·(-1)·16
Δ = 289
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{289}=17$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(15)-17}{2*-1}=\frac{-32}{-2}
=+16
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(15)+17}{2*-1}=\frac{2}{-2}
=-1
$