(x+10)(2x-4)=0

Solution for (x+10)(2x-4)=0 equation:

(x+10)(2x-4)=0

We multiply parentheses ..

(+2x^2-4x+20x-40)=0

We get rid of parentheses

2x^2-4x+20x-40=0

We add all the numbers together, and all the variables

2x^2+16x-40=0

a = 2; b = 16; c = -40;
Δ = b2-4ac
Δ = 162-4·2·(-40)
Δ = 576
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{576}=24$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(16)-24}{2*2}=\frac{-40}{4}
=-10
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(16)+24}{2*2}=\frac{8}{4}
=2
$