9x^2-4x-12x-15x^2=0

Solution for 9x^2-4x-12x-15x^2=0 equation:

9x^2-4x-12x-15x^2=0

We add all the numbers together, and all the variables

-6x^2-16x=0

a = -6; b = -16; c = 0;
Δ = b2-4ac
Δ = -162-4·(-6)·0
Δ = 256
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{256}=16$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-16)-16}{2*-6}=\frac{0}{-12}
=0
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-16)+16}{2*-6}=\frac{32}{-12}
=-2+2/3
$