NinetynineAM–GM bound on a sum of reciprocal-type terms
CAT has tested this idea 5 times across 3 papers, from 2020 to 2023. Solve one, and the others are the same method with different numbers or wording, which is why repeated concepts are the most efficient thing to practise.
| Question | What it asks | Answer |
|---|---|---|
| CAT 2022 Slot 3 · QA Q15 | 16x/y + 49y/x cannot lie in (−56, 56) | C |
| CAT 2023 Slot 2 · QA Q7 | minimum of k/(4y) + 9y after finding k | 6 |
| CAT 2022 Slot 3 · QA Q2 | (x^2 − 6x + 10)/(3 − x) split as t + 1/t | C |
| CAT 2020 Slot 2 · QA Q10 | maximum of x/√(1 + x^4) | C |
| CAT 2020 Slot 2 · QA Q7 | x + y fixed; minimise product with 1/x and 1/y | 2704 |
Part of Inequalities & Modulus (49 questions since 2017).