(2x+4)(-5x-1)=0

Solution for (2x+4)(-5x-1)=0 equation:

(2x+4)(-5x-1)=0

We multiply parentheses ..

(-10x^2-2x-20x-4)=0

We get rid of parentheses

-10x^2-2x-20x-4=0

We add all the numbers together, and all the variables

-10x^2-22x-4=0

a = -10; b = -22; c = -4;
Δ = b2-4ac
Δ = -222-4·(-10)·(-4)
Δ = 324
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{324}=18$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-22)-18}{2*-10}=\frac{4}{-20}
=-1/5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-22)+18}{2*-10}=\frac{40}{-20}
=-2
$