若m是一元二次方程x2-3x-1=0的根,则代数式3m-m2的值为( )
A.0 | B.-1 | C.1 | D.±1 |
更新时间:2022-03-19 06:41:07
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【推荐1】定义:如果代数式
(
,
,
,
是常数)与
(
,
,
,
是常数),满足
,
,
,则称这两个代数式
与
互为“同心式”,下列四个结论:
①代数式:
的“同心式”为
;
②若
与
互为“同心式”,则
的值为1;
③当
时,无论
取何值,“同心式”
与
的值始终互为相反数;
④若
、
互为“同心式”,且
是一个完全平方式,则
.
其中,正确的结论有( )个.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8393062577c3376b5645dae73827b3fd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fc9efeb4455e30293d412938eeea85d5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e72adb45c60c2f63b46e65ff787302bf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b715e7842b95f654f16056a7c7f2abe9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7936359df4c926b72b48c6fdae55f12d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fc74d7e4fa615d30f2b2a7e015e40698.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9ae7c6c2e0772926b35b2672113557d8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3e88093a749c0d46e0ee931ecfaff925.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/13423c094861baf4b759b7f3d8c3c226.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b76f79be89b8c6227b68eded6b675546.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20eec4c0b16de240e078c91716deafd3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8b115aa9eb665405381be36b7fc0538d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9783bc5a9ae68ecd7de1c27d371106d2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
①代数式:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/077acc68430ec78a156eb090ce647736.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/25f66cc4fd5456051f12c2f797dc8243.png)
②若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36f818597c27acb924cceef1f06b51f3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d6ae7dbc37ec05afe46d02931fd3ccda.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b71e9943f2864c9218968f3659251f5e.png)
③当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/eb93c63747322333be537ab0ba03ac36.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
④若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7fd2e0881dea2b5d4938ac48b2b1782d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85cdc6fa2b5a9476a168dfe4b6c4baa0.png)
其中,正确的结论有( )个.
A.1个 | B.2个 | C.3个 | D.4个 |
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单选题
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适中
(0.65)
【推荐2】若
,则关于x的一元二次方程
必有一根为( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c766352f0be38b719621052de92615bd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d9ff52ec8dab4aaac7b28a0efe580d86.png)
A.![]() | B.![]() | C.![]() | D.![]() ![]() |
您最近一年使用:0次