知y=y1-y2,y1与成正比例,y与x成反比例,且当x=1时,y=-14,x=4时,y=3. 求(1)y与x之间的函数关系式. (2)自变量x的取值范围. (3)当x=时,y的值. 答案:(1)y=2- 提示:设y=k1- ,再代入求k1,k2的值. (2)自变量x取值范围是x>0. (3)当x=时,y=2-162=255.;I am not free at weekends because I will ________ my parents.
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A.visit B.call
C.understood D.caught up