Math, asked by saratripathi18, 1 year ago

find the sum of first 15terms having nth term as
an=3+4n

Answers

Answered by MBrainliest
2
nth term = 3 + 4n
.°. 15th term = 3 + 4×15 = 63
=> a15 = a + (15-1)d
=> 63 = 3 + 14d
=> 60 = 14d
=> d = 60/14= 30/7

.°. S15 = 15/2 [2×3 + 14×30/7]
S15 = 15(3 + 30) = 15×33 = 495

Ans : 495

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