Question

Расстояние между пунктами А и В 35 км. Лодка сначала проплыла по течению реки из пункта А в пункт В, а потом обратно. На весь путь лодка затратила 6 часов. Скорость течения реки 2км/ч. Найти скорость лодки . стоячей воде. Нужен ответ срочно пожалуйста

Answer 1

X км/ч - скорость лодки в стоячей воде
х+2 - скорость лодки по течению
х-2 - скорость лодки против течения
35/x+2 -время движения по течению
35/х-2 - время движения против течения
35/x+2 + 35/x-2 =6  переносим всё в левую часть, приводим к общему знаменателю: в числителе 35(x-2)+35(x-2)-6(x-2)(x+2), в знаменателе (x-2)(x+2)
дробь =0 когда числитель =0, а знаменатель нет
35(x-2)+35(x+2)-6(x-2)(x+2)=0
70x-6x^2+24=0
3x^2-35x-12=0
D=35^2-4*3*(-12)=1369
x1=35-37/6=-1/3 не подходит
x2=35+37/6=12  скорость лодки в стоячей воде 12км/ч

Answer 2

Calculating the Speed of the Boat in Still Water

To calculate the speed of the boat in still water, we can use the formula: Speed of boat in still water = (Speed downstream + Speed upstream) / 2

Given: - Distance between points A and B = 35 km - Time taken for the entire journey = 6 hours - Speed of the river's current = 2 km/h

First, let's calculate the speed of the boat downstream and upstream.

Calculating Speed Downstream

The speed of the boat downstream can be calculated using the formula: Speed downstream = (Distance / (Speed of boat + Speed of current))

Using the given values: Speed downstream = (35 / (Speed of boat + 2))

Calculating Speed Upstream

The speed of the boat upstream can be calculated using the formula: Speed upstream = (Distance / (Speed of boat - Speed of current))

Using the given values: Speed upstream = (35 / (Speed of boat - 2))

Solving for the Speed of the Boat

We can use the time taken for the entire journey to find the speed of the boat in still water.

The time taken for the downstream journey is: Time downstream = Distance / (Speed of boat + Speed of current)

The time taken for the upstream journey is: Time upstream = Distance / (Speed of boat - Speed of current)

Given that the total time for the entire journey is 6 hours, we can form the equation: Time downstream + Time upstream = 6

By substituting the calculated values for time downstream and time upstream, we can solve for the speed of the boat in still water.

Let's proceed with the calculations.