问题
填空题
设函数f(x)=
|
答案
由分段函数可知，若x≤1，
由f（x）≤2得，
21-x≤2，即1-x≤1，
∴x≥0，此时0≤x≤1，
若x＞1，
由f（x）≤2得1-log2x≤2，
即log2x≥-1，即x≥
，1 2
此时x＞1，
综上：x≥0，
故答案为：[0，+∞）．
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设函数f(x)=
|
由分段函数可知，若x≤1，
由f（x）≤2得，
21-x≤2，即1-x≤1，
∴x≥0，此时0≤x≤1，
若x＞1，
由f（x）≤2得1-log2x≤2，
即log2x≥-1，即x≥
，1 2
此时x＞1，
综上：x≥0，
故答案为：[0，+∞）．
| 完形填空。 | ||||
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