0=3x^2-30x-12

Solution for 0=3x^2-30x-12 equation:

0=3x^2-30x-12

We move all terms to the left:

0-(3x^2-30x-12)=0

We add all the numbers together, and all the variables

-(3x^2-30x-12)=0

We get rid of parentheses

-3x^2+30x+12=0

a = -3; b = 30; c = +12;
Δ = b2-4ac
Δ = 302-4·(-3)·12
Δ = 1044
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:

$\sqrt{\Delta}=\sqrt{1044}=\sqrt{36*29}=\sqrt{36}*\sqrt{29}=6\sqrt{29}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(30)-6\sqrt{29}}{2*-3}=\frac{-30-6\sqrt{29}}{-6}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(30)+6\sqrt{29}}{2*-3}=\frac{-30+6\sqrt{29}}{-6}
$