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Algebra Difficulty 2.9 Junior Find the answer

If m,nm, n and pp are positive integers with m+1n+1p=173m+\frac{1}{n+\frac{1}{p}}=\frac{17}{3}, what is the value of nn?

A number or a short expression. Spacing and $ signs are ignored.

Solution

Since pp is a positive integer, then p1p \geq 1 and so 0<1p10<\frac{1}{p} \leq 1. Since nn is a positive integer, then n1n \geq 1 and so n+1p>1n+\frac{1}{p}>1, which tells us that 0<1n+1p<10<\frac{1}{n+\frac{1}{p}}<1. Therefore, m<m+1n+1p<m+1m<m+\frac{1}{n+\frac{1}{p}}<m+1. Since m+1n+1p=173m+\frac{1}{n+\frac{1}{p}}=\frac{17}{3}, which is between 5 and 6, and since mm is an integer, then m=5m=5. Since m=5m=5, then m+1n+1p=173m+\frac{1}{n+\frac{1}{p}}=\frac{17}{3} gives 1n+1p=23\frac{1}{n+\frac{1}{p}}=\frac{2}{3} or n+1p=32n+\frac{1}{p}=\frac{3}{2}. Since n<n+1pn+1n<n+\frac{1}{p} \leq n+1 and nn is an integer, then n=1n=1. Thus, n+1p=32n+\frac{1}{p}=\frac{3}{2} gives 1p=12\frac{1}{p}=\frac{1}{2}, which gives p=2p=2. Therefore, n=1n=1.

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