JAMB Mathematics 2021 Objective — Question 38

Question 38 of 40 from the Joint Admissions and Matriculation Board (JAMB) Mathematics 2021 Objective paper, with the correct answer and a full explanation.

38. If 3²ʸ - 6(3ʸ) = 27, find y (a) 2 (b) -1 (c) 1 (d) -2

A. 2Correct
B. -1
C. 1
D. -2

Explanation

Let a = 3ʸ. Then a² - 6a - 27 = 0, which factorises to (a-9)(a+3) = 0, so a = 9 (rejecting the negative value). 3ʸ = 9 = 3², so y = 2.

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