220=(x+4)(2x+6)

Solution for 220=(x+4)(2x+6) equation:

220=(x+4)(2x+6)

We move all terms to the left:

220-((x+4)(2x+6))=0

We multiply parentheses ..

-((+2x^2+6x+8x+24))+220=0


We calculate terms in parentheses: -((+2x^2+6x+8x+24)), so:

(+2x^2+6x+8x+24)

We get rid of parentheses

2x^2+6x+8x+24

We add all the numbers together, and all the variables

2x^2+14x+24

Back to the equation:

-(2x^2+14x+24)


We get rid of parentheses

-2x^2-14x-24+220=0

We add all the numbers together, and all the variables

-2x^2-14x+196=0

a = -2; b = -14; c = +196;
Δ = b2-4ac
Δ = -142-4·(-2)·196
Δ = 1764
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1764}=42$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-14)-42}{2*-2}=\frac{-28}{-4}
=+7
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-14)+42}{2*-2}=\frac{56}{-4}
=-14
$