(x^2)-(2(x))=90

Solution for (x^2)-(2(x))=90 equation:

(x^2)-(2(x))=90

We move all terms to the left:

(x^2)-(2(x))-(90)=0

determiningTheFunctionDomain
x^2-2x-90=0

a = 1; b = -2; c = -90;
Δ = b2-4ac
Δ = -22-4·1·(-90)
Δ = 364
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:

$\sqrt{\Delta}=\sqrt{364}=\sqrt{4*91}=\sqrt{4}*\sqrt{91}=2\sqrt{91}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-2)-2\sqrt{91}}{2*1}=\frac{2-2\sqrt{91}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-2)+2\sqrt{91}}{2*1}=\frac{2+2\sqrt{91}}{2}
$