CAT 2018 Slot 2 — QA Question 24

Given: a² + b² = 97.

AM ≥ GM

⇒ $\frac{{\mathrm{a}}^2+{\mathrm{b}}^2}{2}$ ≥ $\sqrt{{\mathrm{a}}^2\times {\mathrm{b}}^2}$

⇒ 48.5 ≥ |a × b|

⇒ 48.5 ≥ a × b ≥ -48.5

Out of the given options, 64 definitely lies outside this range.

Hence, option (d).