In the evenings into the city and go clubbing or see a movie. a lot of new friends. my pronunciation is much better already, and almost everything. On weekdays Liam. At the moment on their new website and help with it. some useful stuff about how people business in this country.
to see me? the winter holiday skiing with Ryan and Liam. to meet you and there’s plenty of space. You must bring lots of warm clothes because really cold here in the winter. Let me know as soon as . And tell me what these days.
In the evenings into the city and go clubbing or see a movie. a lot of new friends. my pronunciation is much better already, and almost everything. On weekdays Liam. At the moment on their new website and help with it. some useful stuff about how people business in this country.
to see me? the winter holiday skiing with Ryan and Liam. to meet you and there’s plenty of space. You must bring lots of warm clothes because really cold here in the winter. Let me know as soon as . And tell me what these days.
Пусть скорость горной реки х
Плот плывет по реке 21 км в течение 21:х часов
Туристы на лодке все расстояние проплыли за такое же время:
54:(12+х) плыла лодка по реке + 6:12 по озеру и все это равно времени, за которое плот плывет по реке 21 км, =21:х
Составим и решим уравнение:
54:(12+х) +0,5 =21:х
Умножим обе части на х(12+х), чтобы избавиться от дробей:
54х +0,5х(12+х) =21(12+х)
54х +6х +0,5х² =252+21х
0,5х²+39х -252=0
D=b²-4ac=39²-4·0.5·-252=2025
Так как дискриминант больше нуля, то уравнение имеет два корня
Один отрицательный и не подходит ( -84)
Второй = 6
Скорость течения горной реки 6 км/ч