The first term of an arithematic progression (A. P) is the common ratio of a GP and the first term of the same GP is the common difference of the AP. The sum of the first 10 terms of the AP is 155 and the sum of the first two terms of the GP is 9. Find the first term of the AP ?
a. 2 or 3 b. 25/2 or 3 c. 2 or 25/2 d. 1 or 2
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and d, da, da^2 . . .. be the G.P
As per the qs 10/2(2a + 9d) = 155
and d(1+a) = 9
Solving the above two we get r = 25/2 or 2
so ans. c
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