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自变量应满足x≠0
故f(x)的定义域为(-∞,0)∪(0,+∞)
由于
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故f(x)的值域为(-∞,-2)∪(-2,+∞)
(2)任取区间(0,+∞)上两个任意的实数x1,x2,且x1<x2,
则x1>0,x2>0,x2-x1>0,
则f(x1)-f(x2)=(
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x2 |
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x1 |
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x2−x1 |
x1•x2 |
即f(x1)>f(x2)
故函数f(x)=
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x2 |
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x2 |
x2−x1 |
x1•x2 |
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