A math problem requires a process, and a solution method of cows eat grass .

I'll give you the formula, you can do the math yourself! That's better for you!

The problem of cattle grazing, also known as the problem of growth and decline or Newton's pasture, was proposed by the great British scientist Newton in the 17th century. The condition of a typical cow grazing problem is to find how many cows can eat the same grass by assuming that the growth rate of grass is fixed, and the number of days it takes for different numbers of cattle to eat the same grass is different. Because the number of days eaten is different, and the grass grows every day, the stock of grass constantly changes with the number of days the cow eats.

There are four basic formulas commonly used to solve the problem of cattle grazing, which are:

1) Set the amount of grass a cow eats in a day to "1".

1) the growth rate of the grass (the corresponding number of cows, the number of days eaten more, the corresponding number of cows, the number of days eaten less) (the number of days eaten more, the number of days eaten less);

2) The amount of original grass, the number of cattle heads, the number of days eaten, the growth rate of grass, the number of days eaten; `

Cows eat grass. 3) the number of days eaten, the amount of original grass (the number of cows, the growth rate of grass);

4) The number of cattle heads, the amount of grass, the number of days eaten, and the growth rate of grass.

These four formulas are the basis for solving the problem of growth and decline.

Since the grass is constantly growing in the process of grazing in the process of cattle grazing, the key to solving the problem of growth and decline is to find ways to find invariants from change. The original grass on the pasture is unchanged, and although the new grass is changing, the amount of new grass growing every day should be the same because it grows at a uniform rate. It is because of this invariant that the above four basic formulas can be derived.

The problem of cattle grazing is often given that different numbers of cattle eat the same grass, and the field has both the original grass and the new grass that grows every day. Due to the different number of cows that eat grass, find out how many days the grass in the field can be eaten by several cows.

The key to solving the problem is to figure out the known conditions, conduct comparative analysis, and then find the number of new grass growing every day, and then find the amount of original grass in the grassland, and then solve the problem that the question is always asked.

The basic quantitative relationship for this type of problem is:

1.(Number of cows, days of grazing more - number of cows, number of days of grazing) (number of days of eating more - days of eating less) = the amount of new grass growing in the grass per day.

2.Number of cows Grass days - new growth per day Number of grass days = original grass in the meadow.

What grade are you? Wouldn't that simple question be? Alas, too lazy to write.

I found a little bit of information that I once collected and sent it to you, hoping it will be of some help to you.

Newton, the great British scientist, once wrote a book on mathematics. There is a very famous topic in the book about cattle grazing on pastures, which has since been called the "Newtonian problem".

Newton's question goes like this: "There is a pasture with 27 cattle that are known to be raised, and the grass is eaten in six days; Raise 23 cows and eat all the grass in 9 days. If you raise 21 cows, how many days can you eat all the grass on the pasture? And the grass in the pasture grows without faith and care. ”

The general solution to this type of problem is: consider the grass that a cow eats in a day as 1, then there is:

1) The amount of grass eaten by 27 cows for 6 days was: 27 6 162

These 162 include the original grass of the pasture and the new grass of 6 days. ）

2) The amount of grass that 23 cows ate for 9 days was: 23 9 207

These 207 include the pasture's original dantanqi grass and 9-day-old new grass. ）

3) The new grass grows at 1 day: (207 162) (9 6) 15

4) The original grass on the pasture is: 27 6 15 6 72

5) The newly grown grass is enough for 15 cows to eat every day, 21 cows minus 15, and the remaining 6 cows eat the grass of the original pasture:

72 (21 15) 72 6 12 (days).

So it takes 21 cows to eat up the grass on the pasture in 12 days.

Do the math, please.

There is a pasture, if you raise 25 sheep, you can eat all the grass in 8 days; Raise 21 sheep and eat all the grass in 12 days. What if you raise 15 sheep and eat up all the grass growing on the pasture in a few days?

The original amount of grass in the pasture is 1, and the new grass grows x every week;

1 (1-5x)/20*5

1-6x)/16*6

2 (1-5x)/20*5

1-yx)/11y

From (1) we get x = 1 30, and substituting (2) gives y = 8 (days).

1. There are x passengers before the ticket cut, per point.

When the clock arrives at Y passengers, a ticket gate is cut z per minute, and 7 ticket gates are required to be a minute, then there is x+20y=30*4*z

1)x+30y=20*5*z

2)x+ay=7*a*z

3) (1) (2) subtract to obtain the genus.

y=2z1)(2).

x＋25y＝110z

x＝110z-50z＝60z

Substitute x and y into (3) respectively

Get 60Z + 2AZ = 7AZ

z 12 minutes.