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

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

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}
$