ECZ 2018 · GCE Paper 1 — Variation

Two variables x and y have the following corresponding values: when x = 2, y = 20; when x = 3, y = 40; when x = a, y = 104. Given that y varies directly as (x² + 1), find the constant of variation, k.

A. 4
B. 5
C. 20
D. 14

Verified working — step 1

"Varies directly as (x² + 1)" multiplies k onto the WHOLE bracket: y = k(x² + 1).

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Original examination question © Examinations Council of Zambia. Worked solution and commentary © G12 Titan — not to be reproduced without permission.

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Two variables x and y have the following corresponding values: when x = 2, y = 20; when x = 3, y = 40; when x = a, y = 104. Given that y varies directly as (x2 + 1), find the constant of variation, k.

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More Variation questions from past papers

Two variables x and y have the following corresponding values: when x = 2, y = 20; when x = 3, y = 40; when x = a, y = 104. Given that y varies directly as (x² + 1), find the constant of variation, k.