112=(8+x)(7+x)

Solution for 112=(8+x)(7+x) equation:

112=(8+x)(7+x)

We move all terms to the left:

112-((8+x)(7+x))=0

We add all the numbers together, and all the variables

-((x+8)(x+7))+112=0

We multiply parentheses ..

-((+x^2+7x+8x+56))+112=0


We calculate terms in parentheses: -((+x^2+7x+8x+56)), so:

(+x^2+7x+8x+56)

We get rid of parentheses

x^2+7x+8x+56

We add all the numbers together, and all the variables

x^2+15x+56

Back to the equation:

-(x^2+15x+56)


We get rid of parentheses

-x^2-15x-56+112=0

We add all the numbers together, and all the variables

-1x^2-15x+56=0

a = -1; b = -15; c = +56;
Δ = b2-4ac
Δ = -152-4·(-1)·56
Δ = 449
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-15)-\sqrt{449}}{2*-1}=\frac{15-\sqrt{449}}{-2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-15)+\sqrt{449}}{2*-1}=\frac{15+\sqrt{449}}{-2}
$