(1000+10x)(20+x)=0

Solution for (1000+10x)(20+x)=0 equation:

(1000+10x)(20+x)=0

We add all the numbers together, and all the variables

(10x+1000)(x+20)=0

We multiply parentheses ..

(+10x^2+200x+1000x+20000)=0

We get rid of parentheses

10x^2+200x+1000x+20000=0

We add all the numbers together, and all the variables

10x^2+1200x+20000=0

a = 10; b = 1200; c = +20000;
Δ = b2-4ac
Δ = 12002-4·10·20000
Δ = 640000
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{640000}=800$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(1200)-800}{2*10}=\frac{-2000}{20}
=-100
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1200)+800}{2*10}=\frac{-400}{20}
=-20
$