x^2-12x-139=0

Solution for x^2-12x-139=0 equation:

x^2-12x-139=0

a = 1; b = -12; c = -139;
Δ = b2-4ac
Δ = -122-4·1·(-139)
Δ = 700
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:

$\sqrt{\Delta}=\sqrt{700}=\sqrt{100*7}=\sqrt{100}*\sqrt{7}=10\sqrt{7}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-12)-10\sqrt{7}}{2*1}=\frac{12-10\sqrt{7}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-12)+10\sqrt{7}}{2*1}=\frac{12+10\sqrt{7}}{2}
$