Find the sum of 15 terms of the series whose nth term is 4n+1 .

nth term of the Ap is (4n+1)

I TERM= 4+1=5.

II TERM = 8+1=9.

COMMON DIFFERENCE= D= 9-5= 4.

S15 = 15/2  X  [2a + d(N-1)]

  =  15/2  X  [10 + 4(14)]

 = 15/2  X  66

 = 15  X  33

  = 495.

HOPE ITS RIGHT...

THUMBS UP PLEASE...

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