0=-5x(4-x)

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

0=-5x(4-x)

We move all terms to the left:

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

We add all the numbers together, and all the variables

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

We add all the numbers together, and all the variables

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


We calculate terms in parentheses: -(-5x(-1x+4)), so:

-5x(-1x+4)

We multiply parentheses

5x^2-20x

Back to the equation:

-(5x^2-20x)


We get rid of parentheses

-5x^2+20x=0

a = -5; b = 20; c = 0;
Δ = b2-4ac
Δ = 202-4·(-5)·0
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{-(20)-20}{2*-5}=\frac{-40}{-10}
=+4
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(20)+20}{2*-5}=\frac{0}{-10}
=0
$