0=-4(x-10)(x-90)

Solution for 0=-4(x-10)(x-90) equation:

0=-4(x-10)(x-90)

We move all terms to the left:

0-(-4(x-10)(x-90))=0

We add all the numbers together, and all the variables

-(-4(x-10)(x-90))=0

We multiply parentheses ..

-(-4(+x^2-90x-10x+900))=0


We calculate terms in parentheses: -(-4(+x^2-90x-10x+900)), so:

-4(+x^2-90x-10x+900)

We multiply parentheses

-4x^2+360x+40x-3600

We add all the numbers together, and all the variables

-4x^2+400x-3600

Back to the equation:

-(-4x^2+400x-3600)


We get rid of parentheses

4x^2-400x+3600=0

a = 4; b = -400; c = +3600;
Δ = b2-4ac
Δ = -4002-4·4·3600
Δ = 102400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{102400}=320$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-400)-320}{2*4}=\frac{80}{8}
=10
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-400)+320}{2*4}=\frac{720}{8}
=90
$