Let \(S_n\) be sum of the first \(n\) terms of an A.P. If \(S_5 = S_9\), what is the ratio of \(a_3 : a_5\)
Question and options
Let be sum of the first terms of an A.P. If , what is the ratio of
Answer and explanation
Correct answer: A - \(9:5\)
S5=5(a+2d), S9=9(a+4d). Equating: 5a+10d=9a+36d -> a=-6.5d. a3=a+2d=-4.5d, a5=a+4d=-2.5d, so a3:a5 = 9:5.
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