3x(2x-2)-4(x+7)=-4

Solution for 3x(2x-2)-4(x+7)=-4 equation:

3x(2x-2)-4(x+7)=-4

We move all terms to the left:

3x(2x-2)-4(x+7)-(-4)=0

We add all the numbers together, and all the variables

3x(2x-2)-4(x+7)+4=0

We multiply parentheses

6x^2-6x-4x-28+4=0

We add all the numbers together, and all the variables

6x^2-10x-24=0

a = 6; b = -10; c = -24;
Δ = b2-4ac
Δ = -102-4·6·(-24)
Δ = 676
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{676}=26$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-10)-26}{2*6}=\frac{-16}{12}
=-1+1/3
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-10)+26}{2*6}=\frac{36}{12}
=3
$