GreenlightTestPrep wrote:
In a certain the sequence, \(t_n=\frac{t_{n−1}}{t_{n−2}}\) for \(n > 2\). If \(t_1=3\) and \(t_2=5\), then what is the product of the first 54 terms of the sequence?
A) 3/5
B) 1/3
C) 1
D) 5/3
E) 5
Given:
\(t_n=\frac{t_{n−1}}{t_{n−2}}\)\(t_1=3\)
\(t_2=5\)
So, \(t_3=\frac{t_{3−1}}{t_{3−2}}=\frac{t_{2}}{t_{1}}=\frac{5}{3}\)
\(t_4=\frac{t_{4−1}}{t_{4−2}}=\frac{t_{3}}{t_{2}}=\frac{(\frac{5}{3})}{5} =\frac{1}{3} \)
\(t_5=\frac{1}{5} \)
\(t_6=\frac{3}{5} \)
\(t_7=3 \)
\(t_8=5\)
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As we can see, the
pattern repeats itself every 6 terms.
Also notice that the product of the first six terms is 1.
This means the product of the NEXT six terms must also be 1
And the product of the six terms AFTER THAN must be 1 as well
The first 54 terms will consist of nine groups consisting of 6 terms each.
So, the product of the first 54 terms will equal the product of nine 1's
So, the product must equal 1
Answer: C
Cheers,
Brent