6、Al and bill live at apposite ends of the same street.Al had to deliver a parcel at bill’s home,Bill one at Al's home.they started at the same moment,each walked at constant speed and returned home immediately after leaving the parcel at its des

6、Al and bill live at apposite ends of the same street.Al had to deliver a parcel at bill’s home,Bill one at Al's home.they started at the same moment,each walked at constant speed and returned home immediately after leaving the parcel at its des
6、Al and bill live at apposite ends of the same street.Al had to deliver a parcel at bill’s home,Bill one at Al's home.they started at the same moment,each walked at constant speed and returned home immediately after leaving the parcel at its destination.they met the first time at the distance of a yard from Al's home and the second time at the distance of b yards from Bill's home.
⑴how long is the street?(2)if a=300 and b=400,who walk faster?

6、Al and bill live at apposite ends of the same street.Al had to deliver a parcel at bill’s home,Bill one at Al's home.they started at the same moment,each walked at constant speed and returned home immediately after leaving the parcel at its des
AL和Bill住在街的两端,AL要送一个包裹给BILL,而BILL也要送一个包裹给AL,他们同时出发,都以固定的速度,送完包裹后立刻回家.他们在距AL家a的地方第一次相遇,在距Bill家b的地方第二次相遇,
1.这条街有多长?
2.如果a=300 .b=400 ,谁走的更快?

设街长为L，则第一次相遇Al 走了a，bill走了L-a，第二次相遇时Al 走了L+b，bill走了2L-b，第二次相遇Al 和bill共走了（L+b）+（2L-b）=3L，可得出第二次相遇的距离是第一次相遇距离的3倍，则时间也应是3倍，则3×a=L+b，得L=3a-b 如果a=300，b=400 ，则L=3a-b=500
则第一次相遇Al 走了300，bill走了L-a=200，可以看出...

全部展开

设街长为L，则第一次相遇Al 走了a，bill走了L-a，第二次相遇时Al 走了L+b，bill走了2L-b，第二次相遇Al 和bill共走了（L+b）+（2L-b）=3L，可得出第二次相遇的距离是第一次相遇距离的3倍，则时间也应是3倍，则3×a=L+b，得L=3a-b 如果a=300，b=400 ，则L=3a-b=500
则第一次相遇Al 走了300，bill走了L-a=200，可以看出Al 走得更快

收起

1.设街长为L，则第一次相遇Al 走了a，bill走了L-a，第二次相遇时Al 走了L+b，bill走了2L-b，第二次相遇Al 和bill共走了（L+b）+（2L-b）=3L，可得出第二次相遇的距离是第一次相遇距离的3倍，则时间也应是3倍，则3×a=L+b，得L=3a-b
2.如果a=300，b=400 ，则L=3a-b=500
则第一次相遇Al 走了300，bill走了L-a=...

全部展开

1.设街长为L，则第一次相遇Al 走了a，bill走了L-a，第二次相遇时Al 走了L+b，bill走了2L-b，第二次相遇Al 和bill共走了（L+b）+（2L-b）=3L，可得出第二次相遇的距离是第一次相遇距离的3倍，则时间也应是3倍，则3×a=L+b，得L=3a-b
2.如果a=300，b=400 ，则L=3a-b=500
则第一次相遇Al 走了300，bill走了L-a=200，可以看出Al 走得更快

收起

设街长为L，则第一次相遇Al 走了a，bill走了L-a，第二次相遇时Al 走了L+b，bill走了2L-b，第二次相遇Al 和bill共走了（L+b）+（2L-b）=3L，可得出第二次相遇的距离是第一次相遇距离的3倍，则时间也应是3倍，则3×a=L+b，得L=3a-b