(3x+3)*(5x-3)=0

Solution for (3x+3)*(5x-3)=0 equation:

(3x+3)(5x-3)=0

We multiply parentheses ..

(+15x^2-9x+15x-9)=0

We get rid of parentheses

15x^2-9x+15x-9=0

We add all the numbers together, and all the variables

15x^2+6x-9=0

a = 15; b = 6; c = -9;
Δ = b2-4ac
Δ = 62-4·15·(-9)
Δ = 576
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{576}=24$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(6)-24}{2*15}=\frac{-30}{30}
=-1
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(6)+24}{2*15}=\frac{18}{30}
=3/5
$