Question

n th term of a sequence is n2+n divied by 2 write sequence
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Answer 1

Answer:an = n² - n + 1

a1 = 1² - 1 + 1 = 1 - 1 + 1 = 1

a2 = 2² - 2 + 1 = 4 - 2 + 1 = 3

a3 = 3² - 3 + 1 = 9 - 3 + 1 = 7

a4 = 4² - 4 + 1 = 16 - 4 + 1 = 13

a5 = 5² - 5 + 1 = 25 - 5 + 1 = 21

the AP will be 1, 3, 7, 13, 20

d = a2 - a1 = a3 - a2

3 - 1 = 7 - 3

2 = 4 (not equal)

this shows that the sequence is not in AP

as the common difference is not equal

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