1) Kate said, «I haven't seen Roy today». 2) Vicky said, «Where are we going tonight, Jane?» 3) The teacher said to the pupils, «You'll pass your exam next month». 4) Philip said to his friend, «My mother bought me these trainers a week ago». 5) Pam said, «I'll bring you this magazine tomorrow, Jane». 6) The baby-sitter said to the woman, «The children are playing on the playground now». hour ago». 8) Henry said to his sister, «I only had a sandwich for breakfast today». 9) Beth said, «I'm happy to be here again». 10) The policeman said to the woman, «I didn't see your car here five minutes ago». 11) The teacher said, «Why weren't you at school yesterday, Bob?» 12) Angela said, «Will you go shopping tomorrow, Mary?» 13) Laura said, «What are you reading now, Nina?» 14) Andrew said, «Can you find any mistakes here, Paul? » 15) Rachel said, «Are you leaving tomorrow, Sam?» 7) Andy said, «I spoke to my coach an >> переобразуйте !
80-х-расстояние от В до места встречи
т-время, через которое встретились
20мин=20/60=1/3ч
45мин=45/60=3/4ч
х 80-х
= (скорость первого на разных участках равна)
т 1/3
х
= 3(80-х)
т
х
= 240-3х
т
х
т=
240-3х
80-х х
= (скорость второго на разных участках равна)
т 3/4
80-х 4х
=
т 3
3(80-х)
т=
4х
240-3
т=
4х
Приравниваем найденные т
х 240-3х
=
240-3х 4х
(240-3х)²=х*4х
240²-2*240*3х+(3х)²=4х²
57600-1440х+9х²-4х²=0
5х²-1440х+57600=0 разделим на 5
х²-288х+11520=0
Д=(-288)²-4*1*11520=82944 - 46080 = 36864
х1=(-(-288)+√36864)/(2*1)=(288+192)/2=480/2=240 не подходит, т.к. 240>80
х2=(-(-288)-√36864)/(2*1)=(288-192)/2=96/2=48км -расстояние от А до места встречи
48:3/4=48*4/3=16*4=64 км/ч-скорость второго
(80-48):1/3=32*3/1=96 км/ч-скорость первого