170=x^2-8x

Solution for 170=x^2-8x equation:

170=x^2-8x

We move all terms to the left:

170-(x^2-8x)=0

We get rid of parentheses

-x^2+8x+170=0

We add all the numbers together, and all the variables

-1x^2+8x+170=0

a = -1; b = 8; c = +170;
Δ = b2-4ac
Δ = 82-4·(-1)·170
Δ = 744
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:

$\sqrt{\Delta}=\sqrt{744}=\sqrt{4*186}=\sqrt{4}*\sqrt{186}=2\sqrt{186}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(8)-2\sqrt{186}}{2*-1}=\frac{-8-2\sqrt{186}}{-2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(8)+2\sqrt{186}}{2*-1}=\frac{-8+2\sqrt{186}}{-2}
$