(10x+10)(4x+20)=0

Solution for (10x+10)(4x+20)=0 equation:

(10x+10)(4x+20)=0

We multiply parentheses ..

(+40x^2+200x+40x+200)=0

We get rid of parentheses

40x^2+200x+40x+200=0

We add all the numbers together, and all the variables

40x^2+240x+200=0

a = 40; b = 240; c = +200;
Δ = b2-4ac
Δ = 2402-4·40·200
Δ = 25600
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{25600}=160$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(240)-160}{2*40}=\frac{-400}{80}
=-5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(240)+160}{2*40}=\frac{-80}{80}
=-1
$