cynthia5566
幼苗
共回答了14个问题采纳率:78.6% 举报
设静水中船速x,水流速度y
25/(x+y)+16/(x-y)=4.5即25(x-y)+16(x+y)=4.5(x+y)(x-y)
20/(x+y)+20/(x-y)=4.5,即20(x-y)+20(x+y)=4.5(x+y)(x-y)
所以
25(x-y)+16(x+y)=20(x-y)+20(x+y)
5(x-y)=4(x+y)得x=9y
代入得25/10y+16/8y=4.5
即100+80=180y,解得y=1
代入得x=9
答:静水中船速为9千米/小时,水流速度1千米/小时.
1年前
10