X*x-x=756

Solution for X*x-x=756 equation:

X*X-X=756

We move all terms to the left:

X*X-X-(756)=0

We add all the numbers together, and all the variables

-1X+X*X-756=0

Wy multiply elements

X^2-1X-756=0

a = 1; b = -1; c = -756;
Δ = b2-4ac
Δ = -12-4·1·(-756)
Δ = 3025
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{3025}=55$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-1)-55}{2*1}=\frac{-54}{2}
=-27
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-1)+55}{2*1}=\frac{56}{2}
=28
$