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

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

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

We add all the numbers together, and all the variables

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

We multiply parentheses ..

(-10x^2+4x-20x+8)=0

We get rid of parentheses

-10x^2+4x-20x+8=0

We add all the numbers together, and all the variables

-10x^2-16x+8=0

a = -10; b = -16; c = +8;
Δ = b2-4ac
Δ = -162-4·(-10)·8
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*-10}=\frac{-8}{-20}
=2/5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-16)+24}{2*-10}=\frac{40}{-20}
=-2
$