2x(x+4)=39

Solution for 2x(x+4)=39 equation:

2x(x+4)=39

We move all terms to the left:

2x(x+4)-(39)=0

We multiply parentheses

2x^2+8x-39=0

a = 2; b = 8; c = -39;
Δ = b2-4ac
Δ = 82-4·2·(-39)
Δ = 376
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:

$\sqrt{\Delta}=\sqrt{376}=\sqrt{4*94}=\sqrt{4}*\sqrt{94}=2\sqrt{94}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(8)-2\sqrt{94}}{2*2}=\frac{-8-2\sqrt{94}}{4}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(8)+2\sqrt{94}}{2*2}=\frac{-8+2\sqrt{94}}{4}
$