-2x(x+3)=-4

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

-2x(x+3)=-4

We move all terms to the left:

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

We add all the numbers together, and all the variables

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

We multiply parentheses

-2x^2-6x+4=0

a = -2; b = -6; c = +4;
Δ = b2-4ac
Δ = -62-4·(-2)·4
Δ = 68
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:

$\sqrt{\Delta}=\sqrt{68}=\sqrt{4*17}=\sqrt{4}*\sqrt{17}=2\sqrt{17}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-6)-2\sqrt{17}}{2*-2}=\frac{6-2\sqrt{17}}{-4}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-6)+2\sqrt{17}}{2*-2}=\frac{6+2\sqrt{17}}{-4}
$