Why do this problem?
It gives practice in manipulation of polynomials.

Possible approach
An easy lesson starter!

Key question
What is p(x)-q(x)?

Possible extension
Learners can make up their own probems by writing down two polynomials in x and then eliminating x between the expressions. They might be asked to make up such a problem and exchange problems with their partner. Then they can compare and check results in pairs.

Possible support
Try a simpler example such as: find the formula relating p and q where p=x+3 and q=x2.