240=(x+11)(x+3)

Solution for 240=(x+11)(x+3) equation:

240=(x+11)(x+3)

We move all terms to the left:

240-((x+11)(x+3))=0

We multiply parentheses ..

-((+x^2+3x+11x+33))+240=0


We calculate terms in parentheses: -((+x^2+3x+11x+33)), so:

(+x^2+3x+11x+33)

We get rid of parentheses

x^2+3x+11x+33

We add all the numbers together, and all the variables

x^2+14x+33

Back to the equation:

-(x^2+14x+33)


We get rid of parentheses

-x^2-14x-33+240=0

We add all the numbers together, and all the variables

-1x^2-14x+207=0

a = -1; b = -14; c = +207;
Δ = b2-4ac
Δ = -142-4·(-1)·207
Δ = 1024
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1024}=32$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-14)-32}{2*-1}=\frac{-18}{-2}
=+9
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-14)+32}{2*-1}=\frac{46}{-2}
=-23
$