Polynomial roots — Cubic reciprocal sum

Question

Roots of are . Find .

This practice question was inspired by Question 11(h) in the 2021 NSW HSC Mathematics Extension 1 examination, © NESA. It is an original TestMum variation that practises the same mathematical idea, not an official NESA question.

Set up the solution: translate the requested symmetric expression into sums and products of roots from the coefficients..
Finish the calculation, then check that the result meets the question’s conditions.Vieta: , product .
State the final answer clearly in the form the question requested.Sum of reciprocals .

Common mistake: changing so many features that the new example no longer tests the same mathematical idea.

Verification: Answer .

Any mark labels are a TestMum study aid, not an official NESA marking allocation.