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已知向量=(x-1,2),=(4,y),若⊥,则9x+3y的最小值为 .
已知向量
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131103102344469404072/SYS201311031023444694040012_ST/0.png)
=(x-1,2),
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131103102344469404072/SYS201311031023444694040012_ST/1.png)
=(4,y),若
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131103102344469404072/SYS201311031023444694040012_ST/2.png)
⊥
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131103102344469404072/SYS201311031023444694040012_ST/3.png)
,则9
x+3
y的最小值为
.
考点分析:
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