1. The problem statement, all variables and given/known data The problem is this: "Find a linear function f such that (f o f)(x) = 4x + 3. 2. Relevant equations The only hint I've received is "write f(x) = ax + b, and use the given equation to find a and b." 3. The attempt at a solution I've been staring at this thing for almost half an hour now. I'm most confused because I need to find an equation that when composed with itself equals 4x + 3. I've tried to solve for a and b by substituing the 4 and 3 from the final equation as the various variables (a, x, and b), but all those solutions have left me with nothing useful. I also don't understand how I am supposed to solve for a and b when I only have one equation. I obviously don't want the entire solution printed for me, but believe me, I have tried and I cannot get past this problem. Even just a little tip would be great, thanks!