Find the value of x when y = 5, if x varies directly as 4y-1 and x = 14 when y = 2.
Correct answer: A. 38
- A. 38
- B. 35
- C. 10
- D. 28
Explanation
Direct variation means x = k(4y - 1). Using x = 14 when y = 2 gives 14 = k(8 - 1) = 7k, so k = 2; when y = 5, x = 2(20 - 1) = 38. The likely wrong choice is 28, obtained by multiplying the old x by the ratio of the y-values and ignoring the expression 4y - 1.
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