7x^2+18x-18=0

Solution for 7x^2+18x-18=0 equation:

7x^2+18x-18=0

a = 7; b = 18; c = -18;
Δ = b2-4ac
Δ = 182-4·7·(-18)
Δ = 828
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:

$\sqrt{\Delta}=\sqrt{828}=\sqrt{36*23}=\sqrt{36}*\sqrt{23}=6\sqrt{23}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(18)-6\sqrt{23}}{2*7}=\frac{-18-6\sqrt{23}}{14}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(18)+6\sqrt{23}}{2*7}=\frac{-18+6\sqrt{23}}{14}
$