x(x+8)=3

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

x(x+8)=3

We move all terms to the left:

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

We multiply parentheses

x^2+8x-3=0

a = 1; b = 8; c = -3;
Δ = b2-4ac
Δ = 82-4·1·(-3)
Δ = 76
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:

$\sqrt{\Delta}=\sqrt{76}=\sqrt{4*19}=\sqrt{4}*\sqrt{19}=2\sqrt{19}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(8)-2\sqrt{19}}{2*1}=\frac{-8-2\sqrt{19}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(8)+2\sqrt{19}}{2*1}=\frac{-8+2\sqrt{19}}{2}
$