Solution: Let each cow eat 1 serving of grass every day.
9x 12= 108 (copies)
8x 16= 128 (copies)
Planting grass every day:
(128-108)/(16-12) = 5 (copies)
Original grass:
108-5x 12=48 (copies)
128- 16x5=48 (copies)
/kloc-Number of cows to be eaten in 0/2 days:
[48+(5-4)x6]/6+5= 14 (head)
Increase the number of cows:
14-4= 10 (header)
12 days of existing grass quantity:
48+(5-4)x6+5x6=84 (copies)
Or: 48+5x 12-4x6=84 (copies)
Number of edible cows:
84/6= 14 (head)
Need to increase the number of cattle:
14-4= 10 (header)
Nine cows ate 12 days, and the latter also ate 12 days. If you eat the same number of days, then the number of cows eating grass should be the same. Contrast: 4 cows eat for 6 days, 5 cows less than 9 cows eat for 6 days. If you eat for 6 days, you will increase 5 cows compared with 9 cows for 6 days, then you need 14 cows, which will increase 10 cows.
9-4+9-4= 10 (head)
If four cows eat for six days, five fewer than nine cows eat for six days, and 12 days is twice that of six days, then the number of cows that eat grass for 12 days should be twice that of cows that eat grass for six days. A small number of cows means an increase in the number of cows.
(9-4)x2= 10 (head)
According to the topic, we found that the condition of the same pasture is (1): 12 days can eat the grass of 9 cows; (2) Eight cows can also be fed the same grass 16 days. Because grass grows at a constant speed every day, every cow eats the same amount of grass every day.
It can be assumed that the amount of grass eaten by each cow per day is "1".
(1) The grazing amount of 9 cows 12 days is: 9 times 12= 108 (unit).
(2) The grazing amount of 8 cows 16 days is 8 times that of 6 16= 128 (unit).
We observed that (1) and (2) the amount of grass eaten by the same grass is different. Think about it, students. Why?
Oh, it turns out that grass grows at a constant speed every day, and (1) and (2) eat grass at different times, so the amount of grass eaten is different. Then we can find out how much grass grows every day by finding out their differences ... The formula is: (128- 108) divided by (65438+)
Then the original grass quantity: 9 times 12-5 times 12=48 (unit)
Now, the question requires us to find out "how many cows have eaten grass since the seventh day, and then eat all the grass in six days, and ask how many cows have been added since the seventh day", so that we can find out the amount of grass left after four cows ate grass in the first six days.
The formula is: 48-4 times 6+6 times 5=54 (unit). Students, think about it. Why add 5 times 6?
Because the grass grows to 5 units every day, it will grow 5 times 6=30 (units) after 6 days.
Next, we can add some cows and eat all the grass for 6 days.
The formula is 54 divided by 6=9 days.
9-4+5= 10 (days)
Suppose: the original grassland is 1, then the daily grazing amount of each cow is X, and the growth amount of grass is Y.
Unlock ~
Because cows are eating grass, and the grass is growing ~
So there is such a relationship:
The first day:
1-9x+Y
The next day:
1-9X+Y-9X+Y
..... and so on.
Then the relationship between 9 cows eating 12 days is: (find the above rule and simplify ...)
1- 12 * 9X+ 12Y = 0……①
Same as above, so eight cows eat 16 days:
1- 16 * 8X+ 16Y = 0……②
Solution:
X= 1/48
Y=5/48
Look at the topic again ~
Now four cows have eaten for six days, but not on the seventh day.
That is to say, there is such a relationship:
1-4X*6+6Y=？
Just substituting data? = 1. 125
Now suppose there is an extra cow.
That is, (a+4) cows eat 1. 125 forage for 6 days.
That is,1.125-(a+4) x * 6+6y = 0.
Substitute the data to calculate A= 10.
Answer ~ ~ ~