if sn the sum of first n terms of an AP is given by sn =3n sq. -4n ,find the nth term.
Answers
Answered by
11
Step-by-step explanation:
taking n = 1, S1 = a1 = -1
taking n = 2, a2 = S2 - S1 = 4 + 1 = 5
so, d = +6
therefore, an = a + (n-1)*d
= -1 + 6n - 6
= 6n -7
Answered by
3
Answer:
6n - 7
Step-by-step explanation:
Given sum of n terms is
Sn = 3n² - 4n
= 3n²-6n+3-4n+4
= 3n²-10n+7
Sum of n terms is = sum of n-1 terms + nth term.
=> nth term = Sn - Sn-1
= 3n²-4n-(3n²-10n+7)
= 6n-7
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