3600=x(120-x)

Solution for 3600=x(120-x) equation:

3600=x(120-x)

We move all terms to the left:

3600-(x(120-x))=0

We add all the numbers together, and all the variables

-(x(-1x+120))+3600=0


We calculate terms in parentheses: -(x(-1x+120)), so:

x(-1x+120)

We multiply parentheses

-1x^2+120x

Back to the equation:

-(-1x^2+120x)


We get rid of parentheses

1x^2-120x+3600=0

We add all the numbers together, and all the variables

x^2-120x+3600=0

a = 1; b = -120; c = +3600;
Δ = b2-4ac
Δ = -1202-4·1·3600
Δ = 0
Delta is equal to zero, so there is only one solution to the equation

                              Stosujemy wzór:
$x=\frac{-b}{2a}=\frac{120}{2}=60$