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**arturju** Identify the following as arithmetic, geometric, or neither. If the sequence is arithmetic or geometric, write the explicit expression for the nth term.

a. 1, 3, 5, 7,....

~~~ok according to my understanding of the question i have to find the "formula" for this sequence of numbers.. this is what i got:

2n-1 (n = the 'nth' term)

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b. 4, -6, 9, -13.5,....

~~i have no idea how to write an equation for this one..., i was thinking something like (-1)^n-1 for the (+) & (-) changes but i cant figure anything out beyond that...

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c. 1, x^2, x^4, X^6,....