Subject: linear functions- math 11 advanced
Name: Monique
Who are you: Other

solve;

f(f(x)) = 2x + 4 ; if f(x) = 1

Hi Monique,

The statement "if f(x) = 1" tells me you are defining the function f to have the property that f(x) = 1 regardless of the value of x. This is a particularly uninteresting function. It is like a broken bathroom scale that always gives the same weight regardless of who stands on it.

Now look at

f(f(x)) = 2x + 4

What I see is

f(f(x)) = 2x + 4

and f(x) = 1 so this reduces to

f(1) = 2x + 4

But f(x) has that strange property that its value is 1 regardless of the value of x, so
f(1) = 1. Hence your equation is

1 = 2x + 4

Solve for x.

Penny