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

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

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

We add all the numbers together, and all the variables

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

We multiply parentheses ..

(-2X^2+5X-8X+20)=0

We get rid of parentheses

-2X^2+5X-8X+20=0

We add all the numbers together, and all the variables

-2X^2-3X+20=0

a = -2; b = -3; c = +20;
Δ = b2-4ac
Δ = -32-4·(-2)·20
Δ = 169
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{169}=13$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-3)-13}{2*-2}=\frac{-10}{-4}
=2+1/2
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-3)+13}{2*-2}=\frac{16}{-4}
=-4
$