• Free
  • Grade 8
  • f(g(x)), signed

Composing functions worksheets

f(g(2)) means work g(2) first, then feed its answer into f. These free printable worksheets compose two functions and evaluate them, inside rule first.

Kid stuck on one? You don’t just get the sheet.

  • Answer key included
  • Reopen this exact sheet
  • Letter & A4 ready
Ready to printComposing functions
Composing functions worksheet — f(g(x)), signed, free printable with answer key

The answer key prints on a separate page.

What's on this sheet

Composition adds the one reliable mistake to function notation: working the outside first. f(g(2)) is read left to right and worked right to left — find g(2), then put that number into f. Choosing which rule is inside is what a test actually asks, and it is the whole of what this sheet drills.

Why this sheet works

The arithmetic is kept light on purpose so the order is what shows. Every rule is a straight line and every answer is a whole number, so a child is never fighting heavy computation while also tracking which function goes first. What is being practiced is the reading and the sequence, not the sums.

How this one works

One question from this sheet, worked through a step at a time.

f(x) = x, g(x) = −3x + 3; f(g(6))

f(x) = x
g(x) = −3x + 3
g(6)=−15
f(−15)=−15
f(g(6))=−15
  1. f(g(6)) means work the inside first: find g(6), then put THAT answer into f.
  2. g(6): multiply first, −3 × 6 = −18, then −18 + 3 = −15.
  3. Now put −15 into f: 1 × (−15) = −15.
  4. So f(g(6)) = −15.