X+y*X=104

Solution for X+y*X=104 equation:

X+X*X=104

We move all terms to the left:

X+X*X-(104)=0

Wy multiply elements

X^2+X-104=0

a = 1; b = 1; c = -104;
Δ = b2-4ac
Δ = 12-4·1·(-104)
Δ = 417
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{-(1)-\sqrt{417}}{2*1}=\frac{-1-\sqrt{417}}{2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1)+\sqrt{417}}{2*1}=\frac{-1+\sqrt{417}}{2}
$