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在一个不透明的袋中,装有若干个除颜色不同外其余都相同的球,如果袋中有3个红球且摸...
在一个不透明的袋中,装有若干个除颜色不同外其余都相同的球,如果袋中有3个红球且摸到红球的概率为
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103001215972714897/SYS201311030012159727148000_ST/0.png)
,那么袋中球的总个数为( )
A.15个
B.12个
C.9个
D.3个
考点分析:
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细心观察下图,认真分析各式,然后解答问题.
(
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103001208522276703/SYS201311030012085222767023_ST/0.png)
)
2+1=2 S
1=
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103001208522276703/SYS201311030012085222767023_ST/1.png)
(
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103001208522276703/SYS201311030012085222767023_ST/2.png)
)
2+1=3 S
2=
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103001208522276703/SYS201311030012085222767023_ST/3.png)
(
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103001208522276703/SYS201311030012085222767023_ST/4.png)
)
2+1=4 S
3=
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103001208522276703/SYS201311030012085222767023_ST/5.png)
(1)请用含n(n是正整数)的等式表示上述变化规律;
(2)推算出OA
10的长;
(3)求出S
12+S
22+S
22+…+S
102的值.
查看答案
某号台风的中心位于O地,台风中心以25千米/小时的速度向西北方向移动,在半径为240千米的范围内将受影响、城市A在O地正西方向与O地相距320千米处,试问A市是否会遭受此台风的影响?若受影响,将有多少小时?
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对于题目“化简并求值:
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103001208522276703/SYS201311030012085222767021_ST/0.png)
+
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103001208522276703/SYS201311030012085222767021_ST/1.png)
,其中a=
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103001208522276703/SYS201311030012085222767021_ST/2.png)
”,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/20131103001208522276703/SYS201311030012085222767021_ST/3.png)
+
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103001208522276703/SYS201311030012085222767021_ST/4.png)
=
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103001208522276703/SYS201311030012085222767021_ST/5.png)
+
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103001208522276703/SYS201311030012085222767021_ST/6.png)
=
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103001208522276703/SYS201311030012085222767021_ST/7.png)
+
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103001208522276703/SYS201311030012085222767021_ST/8.png)
-a=
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103001208522276703/SYS201311030012085222767021_ST/9.png)
-a=
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103001208522276703/SYS201311030012085222767021_ST/10.png)
;
乙的解答:
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103001208522276703/SYS201311030012085222767021_ST/11.png)
+
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103001208522276703/SYS201311030012085222767021_ST/12.png)
=
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103001208522276703/SYS201311030012085222767021_ST/13.png)
+
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103001208522276703/SYS201311030012085222767021_ST/14.png)
=
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103001208522276703/SYS201311030012085222767021_ST/15.png)
+a-
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103001208522276703/SYS201311030012085222767021_ST/16.png)
=a=
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103001208522276703/SYS201311030012085222767021_ST/17.png)
.
请你判断谁的答案是错误的,为什么?
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已知x,y都是实数,且(x+y-1)
2与
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103001208522276703/SYS201311030012085222767020_ST/0.png)
互为相反数,求实数y
x的负倒数.
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已知:
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103001208522276703/SYS201311030012085222767019_ST/0.png)
,
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103001208522276703/SYS201311030012085222767019_ST/1.png)
,求代数式x
2-xy+y
2值.
查看答案