Question

The sum of first n term of an AP 3n*+4p find its nth term and the AP?solved

Answer 1

Hey there !!

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We have , Sn = 3 n^2 + 4n

If n = 1

Then , S1 = 3 × 1^2 + 4× 1 = 7

If n = 2 Then , S2 = 3×2^2 + 4×2 = 20

We know a2 = S2 - a1 = 20-7 = 13

And d = 13- 7 = 6 Now our required AP is - a , a + d , a + 2d , a + 3d .....

7 , 7 + 6 , 7 + 2×6 , 7+ 3×6

7 , 13 , 19 , 25 ..... Hope this would help u !!