Given f, g and h, verify that f∘(g∘h) = (f∘g)∘h.

1. 1 · Write what is given and what is to be found. Copy f(x), g(x) and h(x), and write the identity to verify.
2. 2 · Write the formula or theorem. Definition: (f∘g)(x) = f(g(x)); the inner function acts first.
3. 3 · Find the left side.
   • Find g∘h first.
   • Substitute it into f to get f∘(g∘h).
4. 4 · Find the right side.
   • Find f∘g first.
   • Substitute h(x) into f∘g to get (f∘g)∘h.
5. 5 · Expand and simplify both sides. Expand every bracket fully, e.g. (2x − 1)² = 4x² − 4x + 1.
6. 6 · Check and box the answer. Show LHS = RHS and write 'Hence verified'.

Scoring tip: Keep g(x) inside brackets when you substitute it. Most lost marks come from a dropped bracket or a wrong sign.