x(x-2)+x+2x+58+12=100

Solution for x(x-2)+x+2x+58+12=100 equation:

x(x-2)+x+2x+58+12=100

We move all terms to the left:

x(x-2)+x+2x+58+12-(100)=0

We add all the numbers together, and all the variables

3x+x(x-2)-30=0

We multiply parentheses

x^2+3x-2x-30=0

We add all the numbers together, and all the variables

x^2+x-30=0

a = 1; b = 1; c = -30;
Δ = b2-4ac
Δ = 12-4·1·(-30)
Δ = 121
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{121}=11$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(1)-11}{2*1}=\frac{-12}{2}
=-6
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1)+11}{2*1}=\frac{10}{2}
=5
$