2024七年级下·江苏·专题练习
1 . 计算:
(1)
;
(2)
.
(1)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cbec0fe003e02670c23c14fb90c4afd5.png)
(2)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d5b3440f4c54cfb421ae1800422b52e2.png)
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2 . 观察以下式子的化简过程:
①
,
②
,
③
,
……
根据以上式子的化简过程,得出规律.完成下列问题:
(1)如果n为正整数,那么
的值为______;
(2)根据以上规律计算:
的值.
①
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1832fab4779d224e8000f49c211139d3.png)
②
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6f2416746b01442db41e72f89b93309e.png)
③
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9f400f1cd6848ac44352ce5563894f3e.png)
……
根据以上式子的化简过程,得出规律.完成下列问题:
(1)如果n为正整数,那么
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42388221a8b19545db7aa38fdf50d129.png)
(2)根据以上规律计算:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ebff2bdef72f335cf24aa4350e8ae16b.png)
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3 . 阅读材料:像
,
,……这种两个含二次根式的代数式相乘,积不含二次根式,我们称这两个代数式互为有理化因式.在进行二次根式运算时,利用有理化因式可以化去分母中的根号.数学课上,老师出了一道题“已知
,求
的值.”
聪明的小明同学根据上述材料,做了这样的解答:
因为
,
所以
.
所以
,所以
,
所以
,所以
,所以
.
请你根据上述材料和小明的解答过程,解决如下问题:
(1)
的有理化因式是 ,
.
(2)化简
.
(3)若
,求
的值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/18ca4c5dfe044315d79a48b0854d7328.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cc8b53dc29f3e6fd05c2a7843aa00f57.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ab27ecd6a820dc891268e3aa55f3e98f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3fd6cc81344ba6f442b2d682ab5f041c.png)
聪明的小明同学根据上述材料,做了这样的解答:
因为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d20338421c3c7703e8466be944641409.png)
所以
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8f85c5f898e62e6cbd49e0845cc399b7.png)
所以
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/abbac0015773638c86fe93d5b68fb9bd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b1c425519a742378cb5e63e94f15c8b2.png)
所以
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/583f333b48a747c4626a2dfc4650bf15.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/79f3deba702f6d0a88dbeed8d601dde6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d560a6f187a70b561e34cb4958b960cc.png)
请你根据上述材料和小明的解答过程,解决如下问题:
(1)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/53204688086b1d0111e91cb49fa0ac61.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76cc0642a2a5e00d5411ffbf2fd8eb73.png)
(2)化简
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a5b4c5a00771013823e5d58086a8ee26.png)
(3)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f38f5b6273c89939ef2f2cb61967b40.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ea335d7b3608c8cd5977088a01c9e616.png)
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4 . 阅读下面的材料并解答后面所给出的问题:
①
,②![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1f075d6404ded0af2ae0540aa3cbe556.png)
两个含二次根式的代数式相乘,若它们的积不含有二次根式,我们就说这两个代数式互为有理化因式,例如:
与
,
与
,数学上将上述把分母变成有理数(式)的过程称为分母有理化,因此,化简一个分母含有二次根式的式子时采用分母、分子同时乘以分母的有理化因式的方法就行了.
(1)
的有理化因式是_________,
的有理化因式是_________.
(2)求
的值;
(3)求
的值.
①
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/31948016d3d90e1b5cd8ec835db46fb5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1f075d6404ded0af2ae0540aa3cbe556.png)
两个含二次根式的代数式相乘,若它们的积不含有二次根式,我们就说这两个代数式互为有理化因式,例如:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a7ffe8515ff6183c1c7775dc6f94bdb8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a7ffe8515ff6183c1c7775dc6f94bdb8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d1f190b17530d81d927c358ac84757a4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c34e01955f8c8fe2f0041b35d8d602a7.png)
(1)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2967337e3fcb228dded64ab0c41a17e0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5a581f283460235482116fbe3ba41efe.png)
(2)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b7bc71a710cce5fb1d9ebc7a831ffbcb.png)
(3)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8f9ba395adf869572ade2a849204cf93.png)
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5 . 如果一个正整数能表示为两个连续偶数的平方差,那么称这个正整数为“幸运数”.如:
,
,
,因此4,12,20都是“幸运数”.
(1)请判断:36_____“幸运数”;(填“是”或“不是”)
(2)下面是两个同学演算后的发现,请判断真假,并说明理由.
①佳佳发现:两个连续偶数
和
(其中k取非负整数)构造的“幸运数”也是4的倍数.
②琪琪发现:2024是“幸运数”.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6d97db6e217a9401024dd82ced228854.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/909caba17c1e14ff9893e40978f2a2ca.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e834429fa22b6511cfbcee77b8a06d10.png)
(1)请判断:36_____“幸运数”;(填“是”或“不是”)
(2)下面是两个同学演算后的发现,请判断真假,并说明理由.
①佳佳发现:两个连续偶数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7a50b6c2fb850cb6699ca261a12ab94f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8b5631bc01b998a4b3fabd9e131699dc.png)
②琪琪发现:2024是“幸运数”.
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6 . 先化简,再求值:
,其中
,
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d0a6238a59cf9712769d2c340d2465bc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7aaf740a6dfe1cbafc0903fb30740224.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6f06408895febc126c2ae409e807349c.png)
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7 . 计算:
(1)
;
(2)
.
(1)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ae003aa6547fc543c911d7af57754f11.png)
(2)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/96022b167585cb90f079cdf906a2cdd0.png)
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8 . 计算:
(1)
;
(2)
.
(1)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ff133e563729a91d09e0cdc115f7183f.png)
(2)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08bcb63cfb7a1c3aa1b47730d278a064.png)
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2024七年级下·浙江·专题练习
9 . 先化简再求值:
(1)
,其中
;
(2)
,其中
.
(1)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/724912a89f34ed128d8a856b26608de0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/707ea658f3a9359f5740d5aab48f7948.png)
(2)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e51380e721b9d55010e4c7c12204006d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6b4707e621f172d717e161057ce5e24.png)
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10 . 计算:
(1)
;
(2)
;
(3)
;
(4)
;
(5)
;
(6)
.
(1)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d589415c4e08e8d2e96f644b0aec9ef9.png)
(2)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1f820873efa6f6477ea9e2a0feab12e6.png)
(3)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c64498496e287f85e66722049dd8bfe5.png)
(4)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f1d7e4f848c3e826cc951bffd50b6027.png)
(5)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0329f083b2090807ea0858e443593347.png)
(6)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f4a0f9a20cd2d5c9f09dd47610dc1897.png)
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