x^2-7x=-8

Solution for x^2-7x=-8 equation:

x^2-7x=-8

We move all terms to the left:

x^2-7x-(-8)=0

We add all the numbers together, and all the variables

x^2-7x+8=0

a = 1; b = -7; c = +8;
Δ = b2-4ac
Δ = -72-4·1·8
Δ = 17
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{-(-7)-\sqrt{17}}{2*1}=\frac{7-\sqrt{17}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-7)+\sqrt{17}}{2*1}=\frac{7+\sqrt{17}}{2}
$