0=(x+30)(x-3)

Solution for 0=(x+30)(x-3) equation:

0=(x+30)(x-3)

We move all terms to the left:

0-((x+30)(x-3))=0

We add all the numbers together, and all the variables

-((x+30)(x-3))=0

We multiply parentheses ..

-((+x^2-3x+30x-90))=0


We calculate terms in parentheses: -((+x^2-3x+30x-90)), so:

(+x^2-3x+30x-90)

We get rid of parentheses

x^2-3x+30x-90

We add all the numbers together, and all the variables

x^2+27x-90

Back to the equation:

-(x^2+27x-90)


We get rid of parentheses

-x^2-27x+90=0

We add all the numbers together, and all the variables

-1x^2-27x+90=0

a = -1; b = -27; c = +90;
Δ = b2-4ac
Δ = -272-4·(-1)·90
Δ = 1089
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1089}=33$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-27)-33}{2*-1}=\frac{-6}{-2}
=+3
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-27)+33}{2*-1}=\frac{60}{-2}
=-30
$