难难难难难难难难……very difficult,pretty difficult

来源：学生作业帮编辑：作业帮分类：数学作业时间：2024/07/15 03:54:20

难难难难难难难难……very difficult,pretty difficult
一木船在水上飘游,通过码头时,一艘摩托艇正经过码头驶向下游距码头15千米的村庄,摩托艇经过0.75小时到达村庄,然后折回,在距村庄9千米的地方遇到小船.问水速是多少?摩托艇在静水中的速度是多少?
我还没学过分式

设摩托艇在静水中的速度是v
水速是x
折回到距村庄9千米的地方用时t
(0.75+t)x=15-9=6
(v+x)0.75=15
(v-x)t=9
解出x1=20,x2=4
对应的t1=无意义,t2=0.75
舍去x=20
解出v=16
所以摩托艇在静水中的速度是16km/h
水速是4km/h

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