9x^2-36x-39=0

Solution for 9x^2-36x-39=0 equation:

9x^2-36x-39=0

a = 9; b = -36; c = -39;
Δ = b2-4ac
Δ = -362-4·9·(-39)
Δ = 2700
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:

$\sqrt{\Delta}=\sqrt{2700}=\sqrt{900*3}=\sqrt{900}*\sqrt{3}=30\sqrt{3}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-36)-30\sqrt{3}}{2*9}=\frac{36-30\sqrt{3}}{18}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-36)+30\sqrt{3}}{2*9}=\frac{36+30\sqrt{3}}{18}
$