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mth 164
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** Question Form_labelMessages **
Question on sequence
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The question is what is the nth term of the sequence suggested by the pattern 3,-9,27,-81?
I know it has something to do with -3 but have not hit on the right pattern.
Please explain this sequence.
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Take successive powers of -3. You get
(-3)^1 = -3
(-3)^2 = 9
(-3)^3 = -27
etc.
Now you want 3, -9, 27, etc.., so just put a - sign in front of each expression. You get
-(-3)^1 = 3
-(-3)^2 = -9
-(-3)^3 = 27
So the nth term of the sequence would be
a_n = - (-3)^n
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