X^2+12x-165=0

Solution for X^2+12x-165=0 equation:

X^2+12X-165=0

a = 1; b = 12; c = -165;
Δ = b2-4ac
Δ = 122-4·1·(-165)
Δ = 804
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:

$\sqrt{\Delta}=\sqrt{804}=\sqrt{4*201}=\sqrt{4}*\sqrt{201}=2\sqrt{201}$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(12)-2\sqrt{201}}{2*1}=\frac{-12-2\sqrt{201}}{2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(12)+2\sqrt{201}}{2*1}=\frac{-12+2\sqrt{201}}{2}
$