Question

The first term and the last term of an AP are 17 and 350 respectively.if the common differencei is 9, how many terms are there and what are their sum

Answer 1

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Answer 2

First term of the A.P =17
Therefore a = 17
Last term of the A.P = 350
Therefore a + (n - 1)d = 350
Common difference of the A.P = 9
Therefore d = 9

Last term = 350
a + (n - 1)d = 350
17 + (n - 1)9 = 350
17 + 9n - 9 = 350
9n + 8 = 350
9n = 342
n = 38

Number of terms in the A.P = 38

Sum of the terms of the A.P = n/2 (a + l)
                                             = 38/2 (17 + 350)
                                             = 19 (367)
                                             = 6973

The sum of the A.P = 6973


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