140=(x+7)(x+4)

Solution for 140=(x+7)(x+4) equation:

140=(x+7)(x+4)

We move all terms to the left:

140-((x+7)(x+4))=0

We multiply parentheses ..

-((+x^2+4x+7x+28))+140=0


We calculate terms in parentheses: -((+x^2+4x+7x+28)), so:

(+x^2+4x+7x+28)

We get rid of parentheses

x^2+4x+7x+28

We add all the numbers together, and all the variables

x^2+11x+28

Back to the equation:

-(x^2+11x+28)


We get rid of parentheses

-x^2-11x-28+140=0

We add all the numbers together, and all the variables

-1x^2-11x+112=0

a = -1; b = -11; c = +112;
Δ = b2-4ac
Δ = -112-4·(-1)·112
Δ = 569
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{-(-11)-\sqrt{569}}{2*-1}=\frac{11-\sqrt{569}}{-2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-11)+\sqrt{569}}{2*-1}=\frac{11+\sqrt{569}}{-2}
$