f(2)=3(1.09)8

Solution for f(2)=3(1.09)8 equation:

f(2)=3(1.09)8

We move all terms to the left:

f(2)-(3(1.09)8)=0

We add all the numbers together, and all the variables

f^2-26.16=0

a = 1; b = 0; c = -26.16;
Δ = b2-4ac
Δ = 02-4·1·(-26.16)
Δ = 104.64
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{-(0)-\sqrt{104.64}}{2*1}=\frac{0-\sqrt{104.64}}{2}
=-\frac{\sqrt{}}{2}
$
$f_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+\sqrt{104.64}}{2*1}=\frac{0+\sqrt{104.64}}{2}
=\frac{\sqrt{}}{2}
$