ECZ 2011 · O-Level Paper 1 — Variation
x varies directly as y and inversely as z2, with constant k = 16 (so x = 16yz2). Find the values of z when x = 4 and y = 25.
- A. z = 10 or z = -10
- B. z = 10 only
- C. z = 5 or z = -5
- D. z = 100
Verified working — step 1
z is squared in the denominator - free z2 first, then remember the square root goes BOTH ways.The full step-by-step working and final answer are included with Premium — checked against ECZ marking standards.
Original examination question © Examinations Council of Zambia. Worked solution and commentary © G12 Titan — not to be reproduced without permission.
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