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八年级数学solution一般
题目
阅读下面材料,并解决问题:
12+1=21(2+1)(21)=21\frac{1}{\sqrt{2}+1}=\frac{\sqrt{2}-1}{(\sqrt{2}+1)(\sqrt{2}-1)}=\sqrt{2}-1
13+2=32(3+2)(32)=32\frac{1}{\sqrt{3}+\sqrt{2}}=\frac{\sqrt{3}-\sqrt{2}}{(\sqrt{3}+\sqrt{2})(\sqrt{3}-\sqrt{2})}=\sqrt{3}-\sqrt{2}
12+3=23(2+3)(23)=23\frac{1}{2+\sqrt{3}}=\frac{2-\sqrt{3}}{(2+\sqrt{3})(2-\sqrt{3})}=2-\sqrt{3}
\ldots \ldots
(1)(1)填空:111+10=\frac{1}{\sqrt{11}+\sqrt{10}}=______;
(2)(2)猜想:当nn是正整数时,1n+1+n=______;(\frac{1}{\sqrt{n+1}+\sqrt{n}}=\_\_\_\_\_\_;(用含nn的式子表示)
(3)(3)计算:12+1+13+2+12+3++12023+2022=______.\frac{1}{\sqrt{2}+1}+\frac{1}{\sqrt{3}+\sqrt{2}}+\frac{1}{2+\sqrt{3}}+\ldots +\frac{1}{\sqrt{2023}+\sqrt{2022}}=\_\_\_\_\_\_.
知识点:实数的运算章节:未标注

答案与解析

答案

(1)111+10=1110(11+10)(1110)=1110\frac{1}{\sqrt{11}+\sqrt{10}}=\frac{\sqrt{11}-\sqrt{10}}{(\sqrt{11}+\sqrt{10})(\sqrt{11}-\sqrt{10})}=\sqrt{11}-\sqrt{10}
故答案为:1110\sqrt{11}-\sqrt{10}
(2)1n+1+n=n+1n(n+1+n)(n+1n)=n+1n(2)\frac{1}{\sqrt{n+1}+\sqrt{n}}=\frac{\sqrt{n+1}-\sqrt{n}}{(\sqrt{n+1}+\sqrt{n})(\sqrt{n+1}-\sqrt{n})}=\sqrt{n+1}-\sqrt{n}
故答案为:n+1n\sqrt{n+1}-\sqrt{n}
(3)12+1+13+2+12+3++12023+2022(3)\frac{1}{\sqrt{2}+1}+\frac{1}{\sqrt{3}+\sqrt{2}}+\frac{1}{2+\sqrt{3}}+\ldots +\frac{1}{\sqrt{2023}+\sqrt{2022}}
=21+32+23++20232022=\sqrt{2}-1+\sqrt{3}-\sqrt{2}+2-\sqrt{3}+\ldots +\sqrt{2023}-\sqrt{2022}
=1+2023=-1+\sqrt{2023}
=20231=\sqrt{2023}-1
故答案为:20231\sqrt{2023}-1.

解析

(1)111+10=1110(11+10)(1110)=1110\frac{1}{\sqrt{11}+\sqrt{10}}=\frac{\sqrt{11}-\sqrt{10}}{(\sqrt{11}+\sqrt{10})(\sqrt{11}-\sqrt{10})}=\sqrt{11}-\sqrt{10}
故答案为:1110\sqrt{11}-\sqrt{10}
(2)1n+1+n=n+1n(n+1+n)(n+1n)=n+1n(2)\frac{1}{\sqrt{n+1}+\sqrt{n}}=\frac{\sqrt{n+1}-\sqrt{n}}{(\sqrt{n+1}+\sqrt{n})(\sqrt{n+1}-\sqrt{n})}=\sqrt{n+1}-\sqrt{n}
故答案为:n+1n\sqrt{n+1}-\sqrt{n}
(3)12+1+13+2+12+3++12023+2022(3)\frac{1}{\sqrt{2}+1}+\frac{1}{\sqrt{3}+\sqrt{2}}+\frac{1}{2+\sqrt{3}}+\ldots +\frac{1}{\sqrt{2023}+\sqrt{2022}}
=21+32+23++20232022=\sqrt{2}-1+\sqrt{3}-\sqrt{2}+2-\sqrt{3}+\ldots +\sqrt{2023}-\sqrt{2022}
=1+2023=-1+\sqrt{2023}
=20231=\sqrt{2023}-1
故答案为:20231\sqrt{2023}-1.

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