第75页 - 江苏版实验班提优训练数学八年级上下册答案

C

D

$解:∵\frac{\sqrt{3}-1}{6}÷\frac{1}{6}=\sqrt{3}-1＜1,$

$∴\frac{\sqrt{3}-1}{6}＜\frac{1}{6}$

$解:∵\frac{1}{\sqrt{2023}-\sqrt{2022}}= \sqrt{2023}+ \sqrt{2022} ，\ $

$\frac{1}{\sqrt{2022}-\sqrt{2021}}= \sqrt{2022}+ \sqrt{2021}，\ $

$且 \sqrt{2023}+ \sqrt{2022}＞ \sqrt{2022}+ \sqrt{2021},\ $

$∴ \sqrt{2023}-\sqrt{2022}＜ \sqrt{2022}-\sqrt{2021}$

＜

A

$解:∵2＜ \sqrt{6}＜3,7＜ \sqrt{57}＜8,\ $

$∴\sqrt{6}+2＜3+2=5， \sqrt{57}-2＞7-2=5，\ $

$∴\sqrt{6}+2＜ \sqrt{57}-2.$

$解:根据平方根的定义可知m-5≥0，$

$即m≥5,\ $

$则4-m＜0,$

$∴\sqrt[{3}]{4-m}＜0\ $

$又 \sqrt{m-5}≥0,$

$∴ \sqrt{m-5}＞\sqrt[{3}]{4-m}$