(2x+16)(2x+12)=72

Solution for (2x+16)(2x+12)=72 equation:

(2x+16)(2x+12)=72

We move all terms to the left:

(2x+16)(2x+12)-(72)=0

We multiply parentheses ..

(+4x^2+24x+32x+192)-72=0

We get rid of parentheses

4x^2+24x+32x+192-72=0

We add all the numbers together, and all the variables

4x^2+56x+120=0

a = 4; b = 56; c = +120;
Δ = b2-4ac
Δ = 562-4·4·120
Δ = 1216
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:

$\sqrt{\Delta}=\sqrt{1216}=\sqrt{64*19}=\sqrt{64}*\sqrt{19}=8\sqrt{19}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(56)-8\sqrt{19}}{2*4}=\frac{-56-8\sqrt{19}}{8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(56)+8\sqrt{19}}{2*4}=\frac{-56+8\sqrt{19}}{8}
$