(30+2x)(40+2x)=0

Solution for (30+2x)(40+2x)=0 equation:

(30+2x)(40+2x)=0

We add all the numbers together, and all the variables

(2x+30)(2x+40)=0

We multiply parentheses ..

(+4x^2+80x+60x+1200)=0

We get rid of parentheses

4x^2+80x+60x+1200=0

We add all the numbers together, and all the variables

4x^2+140x+1200=0

a = 4; b = 140; c = +1200;
Δ = b2-4ac
Δ = 1402-4·4·1200
Δ = 400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{400}=20$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(140)-20}{2*4}=\frac{-160}{8}
=-20
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(140)+20}{2*4}=\frac{-120}{8}
=-15
$