Question

determine o número de termos da pg (1/16,1/8,1/4)

Answer 1

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$a_n= \frac{1}{4} \\ \\ a_1= \frac{1}{16} \\ \\ q= \frac{1}{8} \div \frac{1}{16} = \frac{1}{8} \times \frac{16}{1} =2$

$a_n=a_1.q^{n-1} \\ \\ \frac{1}{4} = \frac{1}{16} .2^{n-1} \\ \\ 2^{-2}=2^{-4}.2^{n-1} \\ \\ 2^{-2}=2^{-4+n-1}= \\ \\ 2^{-2}=2^{-5+n} \\ \\ -2=-5+n \\ n=-2+5 \\ n=3$

A P.G tem 3 termos