F(X)=2x/9x+21

Solution for F(X)=2x/9x+21 equation:

(F)=2F/9F+21

We move all terms to the left:

(F)-(2F/9F+21)=0


Domain of the equation: 9F+21)!=0

F∈R


We get rid of parentheses

F-2F/9F-21=0

We multiply all the terms by the denominator


F*9F-2F-21*9F=0

We add all the numbers together, and all the variables

-2F+F*9F-21*9F=0

Wy multiply elements

9F^2-2F-189F=0

We add all the numbers together, and all the variables

9F^2-191F=0

a = 9; b = -191; c = 0;
Δ = b2-4ac
Δ = -1912-4·9·0
Δ = 36481
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$F_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$F_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{36481}=191$
$F_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-191)-191}{2*9}=\frac{0}{18}
=0
$
$F_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-191)+191}{2*9}=\frac{382}{18}
=21+2/9
$