x2+9x-27=0

Solution for x2+9x-27=0 equation:

x2+9x-27=0

We add all the numbers together, and all the variables

x^2+9x-27=0

a = 1; b = 9; c = -27;
Δ = b2-4ac
Δ = 92-4·1·(-27)
Δ = 189
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:

$\sqrt{\Delta}=\sqrt{189}=\sqrt{9*21}=\sqrt{9}*\sqrt{21}=3\sqrt{21}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(9)-3\sqrt{21}}{2*1}=\frac{-9-3\sqrt{21}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(9)+3\sqrt{21}}{2*1}=\frac{-9+3\sqrt{21}}{2}
$