题目内容
已知![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103201533164142898/SYS201311032015331641428015_ST/0.png)
【答案】分析:因为
是整数,且
=4
,则
是完全平方数,然后求满足条件的最小正整数n.
解答:解:∵
=4
,且
是整数,
∴
是整数,
∴2n+1是完全平方数;
∵2n+1≥0,
∴n≥-
,
∴n的最小正整数值是4.
故答案为:4.
点评:主要考查了乘除法法则和二次根式有意义的条件.二次根式有意义的条件是被开方数是非负数.二次根式的运算法则:乘法法则![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103201533164142898/SYS201311032015331641428015_DA/9.png)
=
.除法法则
=
.解题关键是分解成一个完全平方数和一个代数式的积的形式.
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103201533164142898/SYS201311032015331641428015_DA/0.png)
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103201533164142898/SYS201311032015331641428015_DA/1.png)
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103201533164142898/SYS201311032015331641428015_DA/2.png)
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103201533164142898/SYS201311032015331641428015_DA/3.png)
解答:解:∵
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103201533164142898/SYS201311032015331641428015_DA/4.png)
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103201533164142898/SYS201311032015331641428015_DA/5.png)
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103201533164142898/SYS201311032015331641428015_DA/6.png)
∴
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103201533164142898/SYS201311032015331641428015_DA/7.png)
∴2n+1是完全平方数;
∵2n+1≥0,
∴n≥-
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103201533164142898/SYS201311032015331641428015_DA/8.png)
∴n的最小正整数值是4.
故答案为:4.
点评:主要考查了乘除法法则和二次根式有意义的条件.二次根式有意义的条件是被开方数是非负数.二次根式的运算法则:乘法法则
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103201533164142898/SYS201311032015331641428015_DA/9.png)
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103201533164142898/SYS201311032015331641428015_DA/10.png)
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103201533164142898/SYS201311032015331641428015_DA/11.png)
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103201533164142898/SYS201311032015331641428015_DA/12.png)
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103201533164142898/SYS201311032015331641428015_DA/13.png)
![](http://thumb.zyjl.cn/images/loading.gif)
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