F(x)=9x^2-7

Solution for F(x)=9x^2-7 equation:

(F)=9F^2-7

We move all terms to the left:

(F)-(9F^2-7)=0

We get rid of parentheses

-9F^2+F+7=0

a = -9; b = 1; c = +7;
Δ = b2-4ac
Δ = 12-4·(-9)·7
Δ = 253
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$F_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$F_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$F_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(1)-\sqrt{253}}{2*-9}=\frac{-1-\sqrt{253}}{-18}
$
$F_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1)+\sqrt{253}}{2*-9}=\frac{-1+\sqrt{253}}{-18}
$