9d2+4d-9=0

Solution for 9d2+4d-9=0 equation:

9d^2+4d-9=0

a = 9; b = 4; c = -9;
Δ = b2-4ac
Δ = 42-4·9·(-9)
Δ = 340
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{340}=\sqrt{4*85}=\sqrt{4}*\sqrt{85}=2\sqrt{85}$
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(4)-2\sqrt{85}}{2*9}=\frac{-4-2\sqrt{85}}{18}
$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(4)+2\sqrt{85}}{2*9}=\frac{-4+2\sqrt{85}}{18}
$