(15x-3)(2x+6)=0

Solution for (15x-3)(2x+6)=0 equation:

(15x-3)(2x+6)=0

We multiply parentheses ..

(+30x^2+90x-6x-18)=0

We get rid of parentheses

30x^2+90x-6x-18=0

We add all the numbers together, and all the variables

30x^2+84x-18=0

a = 30; b = 84; c = -18;
Δ = b2-4ac
Δ = 842-4·30·(-18)
Δ = 9216
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{9216}=96$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(84)-96}{2*30}=\frac{-180}{60}
=-3
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(84)+96}{2*30}=\frac{12}{60}
=1/5
$