(2x+2)(x-4)=-5

Solution for (2x+2)(x-4)=-5 equation:

(2x+2)(x-4)=-5

We move all terms to the left:

(2x+2)(x-4)-(-5)=0

We add all the numbers together, and all the variables

(2x+2)(x-4)+5=0

We multiply parentheses ..

(+2x^2-8x+2x-8)+5=0

We get rid of parentheses

2x^2-8x+2x-8+5=0

We add all the numbers together, and all the variables

2x^2-6x-3=0

a = 2; b = -6; c = -3;
Δ = b2-4ac
Δ = -62-4·2·(-3)
Δ = 60
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:

$\sqrt{\Delta}=\sqrt{60}=\sqrt{4*15}=\sqrt{4}*\sqrt{15}=2\sqrt{15}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-6)-2\sqrt{15}}{2*2}=\frac{6-2\sqrt{15}}{4}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-6)+2\sqrt{15}}{2*2}=\frac{6+2\sqrt{15}}{4}
$