Q. 74.6( 5 Votes )

If the sum of thr A. 13

B. 9

C. 21

D. 17

Answer :

Let 3 consecutive terms A.P is a –d, a, a + d. and the sum is 51


So, (a –d) + a + (a + d) = 51


3a –d + d = 51


3a = 51


a = 17


The product of first and third terms = 273


So, (a –d) (a + d) = 273


a2 –d2 = 273


172 –d2 = 273


289 –d 2 = 273


d2 = 289 –273


d2 = 16


d = 4


Third term = a + d = 17 + 4 = 21

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