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设x,y,z∈(0,+∞),a=x+,b=y+,c=z+,则a,b,c三数( )...
设x,y,z∈(0,+∞),a=x+
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,b=y+
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,c=z+
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,则a,b,c三数( )
A.至少有一个不大于2
B.都小于2
C.至少有一个不小于2
D.都大于2
考点分析:
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=
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=
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.
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