(X+10)(3x-12)=0

Solution for (X+10)(3x-12)=0 equation:

(X+10)(3X-12)=0

We multiply parentheses ..

(+3X^2-12X+30X-120)=0

We get rid of parentheses

3X^2-12X+30X-120=0

We add all the numbers together, and all the variables

3X^2+18X-120=0

a = 3; b = 18; c = -120;
Δ = b2-4ac
Δ = 182-4·3·(-120)
Δ = 1764
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1764}=42$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(18)-42}{2*3}=\frac{-60}{6}
=-10
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(18)+42}{2*3}=\frac{24}{6}
=4
$