已知
,
,
,
.
(1)求
的值;
(2)若
,
,求
的值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ddc11a4275eb9a7ccba87e9951a3417d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ead4bb1f4a470e8c51b63c5c24bec1b7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fc9526deb88dc0f09aff9494aef02b71.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3802d26bb1263ac6464281563a0296db.png)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/280860dd039e1305a5ccc455f63e8223.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fcf756a121086c3dc302eb73051e1430.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ff9619d0c33999c86d95c621688f7160.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a989c4fbf0ff34cedb365d2dda47f16.png)
19-20八年级下·湖北武汉·阶段练习 查看更多[4]
湖北省武汉市江汉区2019-2020学年度八年级下学期检测数学试题(已下线)巩固练01 二次根式-2020年【衔接教材·暑假作业】八年级数学(人教版)云南省昭通市昭阳区2022-2023学年八年级下学期5月月考数学试题(已下线)专题02 二次根式的运算7种常考题型归类-【好题汇编】备战2023-2024学年八年级数学下学期期末真题分类汇编(云南专用)
更新时间:2020-05-03 21:00:48
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解答题-计算题
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适中
(0.65)
名校
【推荐1】嘉淇同学计算a+2+
时,是这样做的:
![](https://img.xkw.com/dksih/QBM/2020/6/10/2481427700670464/2484403068502016/STEM/3498ac6286fd415d9fce621fad4a8b03.png?resizew=353)
(1)嘉淇的做法从第 步开始出现错误;正确的计算结果应该是:
(2)计算:
-x-1.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/863b3052928d8040294fa98c77851fa8.png)
![](https://img.xkw.com/dksih/QBM/2020/6/10/2481427700670464/2484403068502016/STEM/3498ac6286fd415d9fce621fad4a8b03.png?resizew=353)
(1)嘉淇的做法从第 步开始出现错误;正确的计算结果应该是:
(2)计算:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d7685fdea87e2c8bd9c4b916c5456fd7.png)
您最近一年使用:0次
解答题-问答题
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【推荐2】观察下面的变形规律:
=1-
;
=
-
;
=
-
;……解答下面的问题:
(1)若n为正整数,请你猜想
= ;
(2)求和:
+
+
.(注:只能用上述结论做才能给分);
(3)用上述相似的方法求和:
.
![](https://img.xkw.com/dksih/QBM/2015/12/24/1573945266880512/1573945272516608/STEM/b3ffc2d3ef0a4c35b96b78312f6d6ddd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f89eef3148f2d4d09379767b4af69132.png)
![](https://img.xkw.com/dksih/QBM/2015/12/24/1573945266880512/1573945272516608/STEM/2973bcee5768463aae434d642650014c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f89eef3148f2d4d09379767b4af69132.png)
![](https://img.xkw.com/dksih/QBM/2015/12/24/1573945266880512/1573945272516608/STEM/97eae53df7a74299acf44744625bdc39.png)
![](https://img.xkw.com/dksih/QBM/2015/12/24/1573945266880512/1573945272516608/STEM/268b88fba7b74f8b9df095b79db874c6.png)
![](https://img.xkw.com/dksih/QBM/2015/12/24/1573945266880512/1573945272516608/STEM/97eae53df7a74299acf44744625bdc39.png)
![](https://img.xkw.com/dksih/QBM/2015/12/24/1573945266880512/1573945272516608/STEM/3c7a8ef2af734aa3b53ba2315289bbbf.png)
(1)若n为正整数,请你猜想
![](https://img.xkw.com/dksih/QBM/2015/12/24/1573945266880512/1573945272516608/STEM/6a2c7f69911149f09b5b2494f6b91ac8.png)
(2)求和:
![](https://img.xkw.com/dksih/QBM/2015/12/24/1573945266880512/1573945272516608/STEM/b3ffc2d3ef0a4c35b96b78312f6d6ddd.png)
![](https://img.xkw.com/dksih/QBM/2015/12/24/1573945266880512/1573945272516608/STEM/2973bcee5768463aae434d642650014c.png)
![](https://img.xkw.com/dksih/QBM/2015/12/24/1573945266880512/1573945272516608/STEM/268b88fba7b74f8b9df095b79db874c6.png)
(3)用上述相似的方法求和:
![](https://img.xkw.com/dksih/QBM/2015/12/24/1573945266880512/1573945272516608/STEM/0b4d1d9b9ba94e95882792d00ae7c7c9.png)
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解答题-计算题
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【推荐1】小明在解决问题,已知
,求
的值,他是这样分析与解答的:
∵
.
∴
.
∴
,即
.
∴
,
∴
.
请你根据小明分析过程的思想方法,解决如下问题:
(1)分母有理化:
______;
(2)计算:
;
(3)若
,求
的值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/80236b37de6f299b5ff05d1ff29850c2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9f3dac8de3d898f0dca07d13691f7140.png)
∵
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/abd737497e5abe51ea41ac298adb99d1.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/781e8ee34a1141016f96356a0f5726d7.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cd8a2c83d7eba31a80d539494c1ec3a6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ab0305b24ae0c310772b0a93f3d92161.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a6601c927f4fa7028557c1f1b128cc2d.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d1e94e2987821583839700f7dd3fc29.png)
请你根据小明分析过程的思想方法,解决如下问题:
(1)分母有理化:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3497ec9206204a7cfbf5ce917f57ddce.png)
(2)计算:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f15ced7c354705f8d6e967aebd6c9fdc.png)
(3)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6ac61e60c71c305d45fd2856cea4e41d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bf5714202e844cf16dcb87816255da8d.png)
您最近一年使用:0次