8x^2+36x-81=0

Solution for 8x^2+36x-81=0 equation:

8x^2+36x-81=0

a = 8; b = 36; c = -81;
Δ = b2-4ac
Δ = 362-4·8·(-81)
Δ = 3888
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:

$\sqrt{\Delta}=\sqrt{3888}=\sqrt{1296*3}=\sqrt{1296}*\sqrt{3}=36\sqrt{3}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(36)-36\sqrt{3}}{2*8}=\frac{-36-36\sqrt{3}}{16}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(36)+36\sqrt{3}}{2*8}=\frac{-36+36\sqrt{3}}{16}
$