SOLUTION: What is the pattern rule with the numbers 7, 21, 63, 189

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Question 950100: What is the pattern rule with the numbers 7, 21, 63, 189
Answer by MathLover1(20850) About Me  (Show Source):
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the pattern rule with the numbers 7, 21, 63, 189
7
21=7%2A3
63=21%2A3=7%2A3%2A3=7%2A3%5E2
189=63%2A3=7%2A3%2A3%2A3=7%2A3%5E3
since the first term a%5B1%5D=7 and using pattern above could be written as a%5B1%5D=7%2A3%5E0 and since n starts with 1, 3%5E0=3%5E%28n-1%29=3%5E%281-1%29
so,the rule is a%5Bn%5D=7%2A3%5E%28n-1%29 for all n=1, 2, 3.....