Question

The sun of first n terms of an apis given by sn=2n^2 + 3n. Find tge 16th term of the ap

Answer 1

Hey !!!

Sn = 2n² + 3n

S1 = 2×1² + 3×1

S1 = 2 + 3

S1 = 5

S1 = t1 = 5 so a = 5

similarly , S2 = 2n² + 3n

S2 = 2×2² + 2×3

S2 = 8 + 6

S2 = 14

S2 = n/2 {2a + (n -1)d}

14 = 2/2 {2×5 + (2-1)d}

14 = 10 + d

4 = d (common difference)

now , t16 = a + (16 -1)d

t16 = 5 + (16 - 1) 4

t16 = 5 + 60

t16 = 65 Answer

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Hope it helps you !!!

@Rajukumar111

Answer 2

The answer is in photograph