0=-3x^2-12x-5

Solution for 0=-3x^2-12x-5 equation:

0=-3x^2-12x-5

We move all terms to the left:

0-(-3x^2-12x-5)=0

We add all the numbers together, and all the variables

-(-3x^2-12x-5)=0

We get rid of parentheses

3x^2+12x+5=0

a = 3; b = 12; c = +5;
Δ = b2-4ac
Δ = 122-4·3·5
Δ = 84
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:

$\sqrt{\Delta}=\sqrt{84}=\sqrt{4*21}=\sqrt{4}*\sqrt{21}=2\sqrt{21}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(12)-2\sqrt{21}}{2*3}=\frac{-12-2\sqrt{21}}{6}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(12)+2\sqrt{21}}{2*3}=\frac{-12+2\sqrt{21}}{6}
$