(x+8)(x-3)=x

Solution for (x+8)(x-3)=x equation:

(x+8)(x-3)=x

We move all terms to the left:

(x+8)(x-3)-(x)=0

We add all the numbers together, and all the variables

-1x+(x+8)(x-3)=0

We multiply parentheses ..

(+x^2-3x+8x-24)-1x=0

We get rid of parentheses

x^2-3x+8x-1x-24=0

We add all the numbers together, and all the variables

x^2+4x-24=0

a = 1; b = 4; c = -24;
Δ = b2-4ac
Δ = 42-4·1·(-24)
Δ = 112
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:

$\sqrt{\Delta}=\sqrt{112}=\sqrt{16*7}=\sqrt{16}*\sqrt{7}=4\sqrt{7}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(4)-4\sqrt{7}}{2*1}=\frac{-4-4\sqrt{7}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(4)+4\sqrt{7}}{2*1}=\frac{-4+4\sqrt{7}}{2}
$