計算第1題
(1)若\((\sqrt{2}-1)^5=\sqrt{m+1}-\sqrt{m}\),則正整數\(m\)之值為何?
(2)請證明存在某一正整數\(m\)滿足:\((\sqrt{2}-1)^{2017}=\sqrt{m+1}-\sqrt{m}\)。
[提示]
利用
\(\begin{align}
& {{\left( \sqrt{2}-1 \right)}^{n}}=\sqrt{a+1}-\sqrt{a} \\
& {{\left( \sqrt{2}+1 \right)}^{n}}=\sqrt{a+1}+\sqrt{a} \\
\end{align}\)
可得\(m=1681\)及證出下一小題
110.11.16補充
證明對於任意自然數\(n\),存在一個自然數\(k\)使得\((\sqrt{2}+1)^n=\sqrt{k}+\sqrt{k-1}\)。
(92高中數學能力競賽 中彰區)
111.2.5補充
給定正整數\(a>b\),對任意正整數\(n\)皆存在正整數\(m\),使得\((\sqrt{a}-\sqrt{b})^n=\sqrt{m+1}-\sqrt{m}\)
試問:
(1)找出並證明符合此條件的所有數對\((a,b)\)
(2)數對\((a,b)\)的方程式\((\sqrt{a}-\sqrt{b})^3=\sqrt{m+1}-\sqrt{m}\),在\(m\)是哪些正整數時,沒有正整數對解?
(109大理高中代理,
https://math.pro/db/thread-3360-1-1.html)
111.3.21補充
Prove that \((\sqrt{2}-1)^n \forall n\in Z^{+}\) can be represented as \(\sqrt{m}-\sqrt{m-1}\) for some \(m\in Z^{+}\).
(1994Canada National Olympiad,
https://artofproblemsolving.com/ ... a_national_olympiad)
113.3.31補充
已知
\(\displaystyle{(\sqrt 2 - 1)^2} = \sqrt 9 - \sqrt 8 \)
\(\displaystyle{(\sqrt 2 - 1)^3} = \sqrt {50} - \sqrt {49} \)
\(\displaystyle{(\sqrt 2 - 1)^4} = \sqrt {289} - \sqrt {288} \)
試證明對於任意正整數\(n\),皆存在正整數\(m\)使得\(\displaystyle{(\sqrt 2 - 1)^n} = \sqrt {m + 1} - \sqrt m \)
(103大直高中,
https://math.pro/db/viewthread.php?tid=1872&page=1#pid10132)