How to do the problem of chickens and rabbits in the same cage in primary school, and how to do the

If there are x chickens, then the rabbits have (100-x), get.

2x=4(100-x)-28

2x=400-4x-28

2x+4x=400-28

6x=372

x = 62 rabbits have (100-x) = 100-62 = 38 A: 62 chickens and 38 rabbits.

Assuming that there are x chickens and y rabbits, the following two formulas can be obtained:

x+y=100

4y-2x=28

From Eq. 1 we get x=100-y

4y-2(100-y)=28

Get 4y-200+2y=28

6y=228

y=38, so x=100-38=62

So there are 62 chickens and 38 rabbits.

Untie rabbit x only.

4x-2(100-x)=28x=38

A: 38 rabbits and 62 chickens.

Let the rabbit's feet be x x divided by 4 + (x-28) divided by 2=100 and the solution is: x=152 then 38 chickens and 62 chickens.

Solution to the problem of chickens and rabbits in the same cage:

1) Hypothetical method.

2) Equation method.

The details are as follows:

There are several chickens and rabbits in the same cage, counting from above, with 35 heads, and counting from below, with 94 legs. Find the number of chickens and rabbits.

1) Hypothetical method.

Suppose it's all chickens: 2 35 = 70 (only).

Chicken feet are less than the total number of feet: 94 70 = 24 (pcs).

The number of feet that rabbits have more than chickens: 4-2=2 (only).

Number of rabbits: 24 2=12 (only).

Number of chickens: 35 12 = 23 (chickens).

2) Equation method.

In the unary equation, if there are x rabbits, then there are (35-x) chickens. 4x+2（35-x）=94。

In a binary equation, let there be x rabbits and y chickens. x+y=35，4x+2y=94。

The solution for the fourth grade of primary school in the same cage of chickens and rabbits is as follows:

1. Assuming that 40 heads are chickens, then there should be enough 2 40 = 80 (only), which is 100-80 = 20 (only) less than the actual one. This is because rabbits are seen as chickens. If you think of a rabbit as a chicken, the number of feet will be 4-2=2 (only) less.

Thus rabbits have 20 2 = 10 (birds) and chickens have 40-10 = 30 (birds).

2. Assuming that 40 heads are rabbits, then there should be enough 4 40 = 160 (only), which is 160-100 = 60 (only) more than the actual one. This is because chickens are seen as rabbits. And if you look at a chicken as a rabbit, the number of feet will be 4-2=2 (only) more.

So chickens have 60 2 = 30 (only) and rabbits have 40-30 = 10 (only).

3. Assuming that 100 feet are chicken feet, then there should be the first 100 2=50 (pieces), which is 50-40 = 10 (pieces) more than the actual one. If you think of a rabbit's feet as chicken feet, the number of rabbits (heads) will increase by 4 2 times, that is, the number of rabbits will increase by (4 2-1) times. Thus rabbits have 10 (4 2-1) = 10 (birds) and chickens have 40-10 = 30 (birds).

4. Assuming that 100 feet are rabbit feet, then there should be a head 100 4=25 (pieces), which is 40-25=15 (pieces) less than the actual one. If you think of a chicken's feet as rabbit feet, the number of chickens (heads) will be reduced by 4 2 times, i.e., the number of chickens will be reduced by 1-1 (2 4) = 1 2. Thus chickens have 15 1 2 = 30 (birds) and rabbits have 40-30 = 10 (birds).

1. One person carries two buckets of water, and two people carry one bucket of water, both with a flat pole.

Set 25 buckets are carried by people, 25 flat shoulders are needed, and a total of 20 flat shoulders are used, 5 less shoulders, less these 5 are picked by people, 5 people 5 flat poles 10 buckets, and the remaining 15 flat poles 15 buckets, exactly 30 people carry.

So 30 people carried the water and 5 people carried the water.

2. Suppose that Kobayashi gets 20*5=100 points, and he only gets 65 points, 100-65=35 points, that is, he gets 35 (2+5)=5 questions wrong (7 points less than all the correct ones for each wrong one).

So he gets 20-5=15 questions right.

3. After changing, the feet increase by 240-228 = 12, and the feet of each less chicken will increase by 2, so there are 6 less chickens and 6 more rabbits. That is, there were 6 more chickens than rabbits. If there are x rabbits, then the chickens are (x+6).

So (x+6)*2+x*4=228, the solution is x=36, that is, 36 rabbits and 42 chickens.

4. A total of 120 points were scored, of which Honghong scored 16 points more than Pingping, indicating that Honghong scored 68 points and Pingping scored 52 points.

The number of red and red shots = (10*10-68) (10+6) = 2, that is, 10-2 = 8 shots in red and red.

The number of unhit shots = (10*10-52) (10+6)=3, that is, 10-3 = 7 hits.

The principle is the same as that of Question 2).

5. If 12 are dragonflies and cicadas, there are 12*6=72 legs, but in reality there are only 66 legs, which is 72-66=6 less

For every one less dragonfly or cicada, there is one more frog, and there are 2 fewer legs, so there are 6 2 = 3 frogs.

So there are 12-3=9 dragonflies and cicadas, and if these 9 are all dragonflies, the wings are 9*2=18, so the cicadas have (18-14) (2-1)=4 (the principle is the same as that of frogs), so dragonflies have 9-4=5.

That is, there are 3 frogs, 5 dragonflies, and 4 cicadas.

The above method is the solution to the chicken-rabbit cage problem, of course, each problem can also be calculated by column equations.

If you are carrying water, each person should have 1 flat pole and 2 buckets.

20 poles correspond to 20 2 = 40 barrels.

Difference: 40-25=15.

Carry water, 1 2 = buckets per person.

Number of people carrying water: 15 (person.)

Number of people carrying water: 20-10 = 10 people.

If all 20 questions are correct, you can get: 20 5 = 100 points.

If you get one question wrong, you will get less: 5 + 2 = 7 points.

Error: (100-65) 7=5.

Get it right: 20-5=15 questions.

A total of (228+240) (4+2)=78 chickens and rabbits.

If 78 are all chickens with legs: 78 2 = 156.

Rabbits (228-156) (4-2) = 36.

That is: 78-36 = 42 pcs.

Red Red Total Score: (120 + 16) 2 = 68 points.

Red-red off-target: (10 10-68) (10+6) = 2 shots.

Red-red hits: 10-2 = 8 rounds.

Average total score: 120-68 = 52 points.

Flat off target: (10 10-52) (10+6) = 3 shots.

Flat hits: 10-3 = 7 rounds.

Assuming that each critter is 6 legs, there is a total of:

12 6 = 72 legs.

Difference: 72-66 = 6 bars.

6-4 = 2 less per frog.

Frogs: 6 2 = 3 pcs.

Dragonflies and cicadas total: 12-3 = 9.

Suppose all 9 dragonflies have a total of 9 2 = 18 pairs of wings.

Difference: 18-14 = 4 pairs.

Cicadas: 4 (2-1) = 4 cicadas.

Dragonfly: 9-4=5 pcs.

1.It is known that 20 buckets and 25 buckets are used to carry water, that is, there are 5 more units carrying water than carrying water, so the answer is 5 people who carry water and 30 people who carry water.

2.Set x questions correctly and y questions incorrectly, x+y=20, 5x-2y=65, solve, x=15, y=5.

3.The chicken has only two legs, the rabbit has 4 legs, and the chicken has x and the rabbit has y, 2x+4y=228, 4x+2y=240, and the solution is x=42, y=36.

4.Let the red red hit x hair, the flat hit y hair, 10x+6(10-x)+10y+6(10-y)=120, 10x+6(10-x)-10y+6(10-y)=16, the solution is x=8, y=7.

5.Let there be x frogs, dragonflies and cicadas have y, x+y=12, 4x+6y=66, and x=3, y=9.

Let the dragonfly have a and the cicada have b, a+b=9, 2a+b=14, and the solution is a=5, b=4

Finally, there were 3 frogs, 5 dragonflies, and 4 cicadas.

Because it is an elementary school, it is important to build the idea of mathematical modeling. Thinking is important.

Hope it helps you ...

1.There were 5 people who carried water and 30 people who carried water.

2.15 true, 5 false.

Chickens 36 rabbits.

Red Red Total Score: (120 + 16) 2 = 68 points.

Red-red off-target: (10 10-68) (10+6) = 2 shots.

Red-red hits: 10-2 = 8 rounds.

Average total score: 120-68 = 52 points.

Flat off target: (10 10-52) (10+6) = 3 shots.

Flat hits: 10-3 = 7 rounds.

5 frogs and 4 dragonflies.

1. What is carrying water?

2. Will the teacher make a mistake?

3. Is there any variation?

4. Will the referee read the wrong one or someone bribe the referee?

5. Have you ever been tortured by humans?

1.There were 5 people who carried water and 30 people who carried water.

2.15 true, 5 false.

Chickens 36 rabbits.

4.Honghong hit 8 shots and Ping Ping hit 7 shots.

5 frogs and 4 dragonflies.

Let's say he's all right.

Wrong: [20 times 5-65] divided by [5+2] = 5 lanes.

Do it right: 20-5 = 15 channels.