3-2x(x+4)=-13

Solution for 3-2x(x+4)=-13 equation:

3-2x(x+4)=-13

We move all terms to the left:

3-2x(x+4)-(-13)=0

We add all the numbers together, and all the variables

-2x(x+4)+16=0

We multiply parentheses

-2x^2-8x+16=0

a = -2; b = -8; c = +16;
Δ = b2-4ac
Δ = -82-4·(-2)·16
Δ = 192
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:

$\sqrt{\Delta}=\sqrt{192}=\sqrt{64*3}=\sqrt{64}*\sqrt{3}=8\sqrt{3}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-8)-8\sqrt{3}}{2*-2}=\frac{8-8\sqrt{3}}{-4}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-8)+8\sqrt{3}}{2*-2}=\frac{8+8\sqrt{3}}{-4}
$