2015 · Q94
If x = 91/216, then the value of 3 − 1/∛(1 − x) is
Elementary MathematicsTrigonometry
- A9/5
- B5/9
- C4/9
- D4/5
Explanation
This tests recognizing perfect cubes hidden in fractions. 1 - x = 1 - 91/216 = 125/216 = 5³/6³, so ∛(1-x) = 5/6. Then 3 - 1/(5/6) = 3 - 6/5 = 9/5. Option (d) 4/5 is the trap from computing 1 - 5/6 (forgetting the reciprocal). Hence option (a).