# Finding the general expression of the nth term

by superconduct
Tags: expression, term
 P: 21 1. The problem statement, all variables and given/known data Given successive terms of numbers starting from the 1st term: 11, 21, 35, 53, 75, 101,... What is the general expression of the nth term? where n is positive integer 2. Relevant equations / 3. The attempt at a solution Can't find a good attempt.
 Mentor P: 16,698 Could this be an arithmetic or geometric sequence??
HW Helper
P: 2,885
 Quote by superconduct 1. The problem statement, all variables and given/known data Given successive terms of numbers starting from the 1st term: 11, 21, 35, 53, 75, 101,... What is the general expression of the nth term? where n is positive integer 2. Relevant equations / 3. The attempt at a solution Can't find a good attempt.
Form a new sequence from the differences between successive terms.

P: 21

## Finding the general expression of the nth term

sorry I don't know...

how will you determine a general expression for it in this problem without trial and error?

is it like finding a needle in the ocean?
 P: 2,491 look at the terms, then form a sequences of differences and what do you get? 10 , 14, 18, 22, 26 ... look at the differences as a sequence and what do you see? write an expression to generate the differences sequence term(n)= term(0) + 4*(n-1) where n=1, 2, 3, 4... then write an expression to generate your sequence using the differences expression TERM(n) = TERM(0) + ...
 P: 9 Ouw... I think you can use the Sn to calculate the Un...

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