Question

the sum of first 'n' terms of an arithmetic sequence is 3n²+5n. find the nth term​

Answer 1

Answer:

nth term = 6n + 10

Step-by-step explanation:

sum of nth term = n/2 [ 2a + (n-1)d ]

so, 3n²+5n = n/2 [ 2a + (n-1)d ]

n ( 3n + 5 ) = n/2 [2a + (n-1)d ]

3n + 5 = 1/2 [2a + (n-1)d ]

6n+10 = 2a + (n-1)d

6n + 10 = nth term

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