-7x^2+-2x-9=0

Solution for -7x^2+-2x-9=0 equation:

-7x^2+-2x-9=0

We add all the numbers together, and all the variables

-7x^2-2x=0

a = -7; b = -2; c = 0;
Δ = b2-4ac
Δ = -22-4·(-7)·0
Δ = 4
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{4}=2$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-2)-2}{2*-7}=\frac{0}{-14}
=0
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-2)+2}{2*-7}=\frac{4}{-14}
=-2/7
$