JAMB Mathematics 2018 Objective — Question 28

Question 28 of 39 from the Joint Admissions and Matriculation Board (JAMB) Mathematics 2018 Objective paper, with the correct answer and a full explanation.

If the sum of the first two terms of a G.P is 3, and the sum of the second and third terms is −6, find the sum of the first term and the common ratio

A. −5Correct
B. −3
C. 2
D. -2

Explanation

a+ar=3 → a(1+r)=3. ar+ar²=−6 → ar(1+r)=−6. Dividing: r=−2. Then a(1−2)=3 → −a=3 → a=−3. Sum a+r = −3+(−2) = −5.

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