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下列事件为必然事件的是( ) A.中秋节晚上一定能看到月亮 B.明天的气温一定会...
下列事件为必然事件的是( )
A.中秋节晚上一定能看到月亮
B.明天的气温一定会比今天的高
C.某彩票中奖率是1%,买100张彩票一定会中奖
D.地球上,上抛的篮球一定会下落
考点分析:
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A.40°
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在直角坐标系中,点(-3,1)关于坐标原点的对称点的坐标为( )
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C.(3,-1)
D.(3,1)
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对于题目“化简并求值:
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+
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,其中a=
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”,甲、乙两人的解答不同.
甲的解答:
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103001126545333403/SYS201311030011265453334031_ST/3.png)
+
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103001126545333403/SYS201311030011265453334031_ST/4.png)
=
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=
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+
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103001126545333403/SYS201311030011265453334031_ST/8.png)
-a=
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-a=
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;
乙的解答:
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103001126545333403/SYS201311030011265453334031_ST/11.png)
+
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103001126545333403/SYS201311030011265453334031_ST/12.png)
=
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+
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=
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+a-
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=a=
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.
请你判断谁的答案是错误的,为什么?
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相信你能成功!
已知a,b,c为三角形的三边,化简
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103001126545333403/SYS201311030011265453334029_ST/0.png)
.
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