-X^2-12x+30=0

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

-X^2-12X+30=0

We add all the numbers together, and all the variables

-1X^2-12X+30=0

a = -1; b = -12; c = +30;
Δ = b2-4ac
Δ = -122-4·(-1)·30
Δ = 264
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:

$\sqrt{\Delta}=\sqrt{264}=\sqrt{4*66}=\sqrt{4}*\sqrt{66}=2\sqrt{66}$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-12)-2\sqrt{66}}{2*-1}=\frac{12-2\sqrt{66}}{-2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-12)+2\sqrt{66}}{2*-1}=\frac{12+2\sqrt{66}}{-2}
$