11000=(x+20)*(x+10)

Solution for 11000=(x+20)*(x+10) equation:

11000=(x+20)(x+10)

We move all terms to the left:

11000-((x+20)(x+10))=0

We multiply parentheses ..

-((+x^2+10x+20x+200))+11000=0


We calculate terms in parentheses: -((+x^2+10x+20x+200)), so:

(+x^2+10x+20x+200)

We get rid of parentheses

x^2+10x+20x+200

We add all the numbers together, and all the variables

x^2+30x+200

Back to the equation:

-(x^2+30x+200)


We get rid of parentheses

-x^2-30x-200+11000=0

We add all the numbers together, and all the variables

-1x^2-30x+10800=0

a = -1; b = -30; c = +10800;
Δ = b2-4ac
Δ = -302-4·(-1)·10800
Δ = 44100
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{44100}=210$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-30)-210}{2*-1}=\frac{-180}{-2}
=+90
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-30)+210}{2*-1}=\frac{240}{-2}
=-120
$