-3x2+15x2-20x+6=0

Solution for -3x2+15x2-20x+6=0 equation:

-3x^2+15x^2-20x+6=0

We add all the numbers together, and all the variables

12x^2-20x+6=0

a = 12; b = -20; c = +6;
Δ = b2-4ac
Δ = -202-4·12·6
Δ = 112
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{112}=\sqrt{16*7}=\sqrt{16}*\sqrt{7}=4\sqrt{7}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-20)-4\sqrt{7}}{2*12}=\frac{20-4\sqrt{7}}{24}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-20)+4\sqrt{7}}{2*12}=\frac{20+4\sqrt{7}}{24}
$