求下列函数的定义域:(1)f(x)= ;(2)f(x)= ;(3)f(x)= + .
求下列函数的定义域:(1)f(x)=;(2)f(x)=;(3)f(x)=+....
求下列函数的定义域:(1)f(x)= ;(2)f(x)= ;(3)f(x)= + .
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2015-01-19
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(1) {x|x≠2}; (2) {x|x≥- ![](https://iknow-pic.cdn.bcebos.com/a1ec08fa513d26976997c2ef56fbb2fb4316d838?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto) }; (3) {x|x≥-1且x≠2} |
解:(1)∵x-2=0,即x=2时,分式 ![](https://iknow-pic.cdn.bcebos.com/8b13632762d0f703baf65f6e0bfa513d2697c538?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto) 无意义, ∴这个函数的定义域是{x|x≠2}. (2)当3x+2≥0,即x≥- ![](https://iknow-pic.cdn.bcebos.com/a1ec08fa513d26976997c2ef56fbb2fb4316d838?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto) 时,根式 ![](https://iknow-pic.cdn.bcebos.com/f603918fa0ec08fa7f44d9155aee3d6d55fbda38?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto) 有意义, ∴这个函数的定义域是{x|x≥- ![](https://iknow-pic.cdn.bcebos.com/a1ec08fa513d26976997c2ef56fbb2fb4316d838?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto) }. (3)要使函数有意义,必须 ∴这个函数的定义域是{x|x≥-1且x≠2}. |
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