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## mollyann Group Title Find the next three terms of the sequence. Then write a rule for the sequence. 648, 216, 72, 24 one year ago one year ago

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1. oldrin.bataku Group Title

By quick observation the difference between the terms is not constant, so the sequence isn't arithmetic. It does, however, appear to be geometric:$$r=\frac{216}{648}=\frac{72}{216}=\frac{24}{72}=\frac13$$... which means we can find the next three terms by multiplying by $$\frac13$$:$$\frac13(24)=8;\frac13(8)=\frac83;\frac13\left(\frac83\right)=\frac89$$The explicit form of a geometric series is $$a_n=a_1r^{n-1}$$; in our case, we've identified $$r=\frac13,\ a_1=658$$ which yields $$a_n=658\left(\frac13\right)^{n-1}$$

2. oldrin.bataku Group Title

648 **