WAEC Further Mathematics 2022 Objective — Question 19

Question 19 of 40 from the West African Examinations Council (WAEC) Further Mathematics 2022 Objective paper, with the correct answer and a full explanation.

Solve 3^(2x−2) − 28(3^(x−2)) + 3 = 0.

A. x=−2 or x=1
B. x=0 or x=−3
C. x=2 or x=1
D. x=0 or x=3Correct

Explanation

Dividing through by 3⁻² and letting y=3ˣ gives y²−28y+27=0, i.e. (y−27)(y−1)=0, so 3ˣ=27 or 3ˣ=1, giving x=3 or x=0.

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