9z^2+18z+7=0

Solution for 9z^2+18z+7=0 equation:

9z^2+18z+7=0

a = 9; b = 18; c = +7;
Δ = b2-4ac
Δ = 182-4·9·7
Δ = 72
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$z_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$z_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{72}=\sqrt{36*2}=\sqrt{36}*\sqrt{2}=6\sqrt{2}$
$z_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(18)-6\sqrt{2}}{2*9}=\frac{-18-6\sqrt{2}}{18}
$
$z_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(18)+6\sqrt{2}}{2*9}=\frac{-18+6\sqrt{2}}{18}
$