(x+30)(x-11)=0

Solution for (x+30)(x-11)=0 equation:

(x+30)(x-11)=0

We multiply parentheses ..

(+x^2-11x+30x-330)=0

We get rid of parentheses

x^2-11x+30x-330=0

We add all the numbers together, and all the variables

x^2+19x-330=0

a = 1; b = 19; c = -330;
Δ = b2-4ac
Δ = 192-4·1·(-330)
Δ = 1681
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1681}=41$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(19)-41}{2*1}=\frac{-60}{2}
=-30
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(19)+41}{2*1}=\frac{22}{2}
=11
$