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

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

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

We move all terms to the left:

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

We multiply parentheses ..

-((+2x^2+16x+4x+32))+72=0


We calculate terms in parentheses: -((+2x^2+16x+4x+32)), so:

(+2x^2+16x+4x+32)

We get rid of parentheses

2x^2+16x+4x+32

We add all the numbers together, and all the variables

2x^2+20x+32

Back to the equation:

-(2x^2+20x+32)


We get rid of parentheses

-2x^2-20x-32+72=0

We add all the numbers together, and all the variables

-2x^2-20x+40=0

a = -2; b = -20; c = +40;
Δ = b2-4ac
Δ = -202-4·(-2)·40
Δ = 720
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:

$\sqrt{\Delta}=\sqrt{720}=\sqrt{144*5}=\sqrt{144}*\sqrt{5}=12\sqrt{5}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-20)-12\sqrt{5}}{2*-2}=\frac{20-12\sqrt{5}}{-4}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-20)+12\sqrt{5}}{2*-2}=\frac{20+12\sqrt{5}}{-4}
$