Please ask everyone a question, the gods help, a question

I'm a primary school student, and I've been in junior high school for a few days, and I just did the math, and the hero solution above is a bit wrong.

I used a stupid method, I don't know if it was right

Set: Zhang Ming's average inventory in 1 hour is n, Li Qiang's average inventory in 1 hour is m, the total number of books is Z, and it takes X hours for Li Qiang to count this batch of books alone.

Solution: Vertical equation.

1) 4n=z 2 (Zhang Ming counted half of a batch of books in 4 hours).

2)(m+n)*1=z 2 (Li Qiang joined the work of counting the other half of the books, and the two worked together to count the other half of the books in 1 hour).

3) 4n+m+n=z (Zhang Ming counted half of a batch of books in 4 hours, Li Qiang joined the work of counting the other half of the books, and the two cooperated to count the other half of the books in 1 hour).

4) x=z m (it takes x hours to count this batch of books individually).

According to 1) and 2), we get: 4n = m + n, m = 3n

Substituting m=3n into 3), we get: n=z 8, m = 3z 8

Substituting m=3z8 into 4), we get x=8 for 3 h.

Test: Substitute n=z8 and m=3z8 into 1) and 2) respectively.

1) 4n=z2 => 4z8=z2 holds.

2)(m+n)*1=z 2 => (3z 8+z 8)=z 2 holds.

It takes X hours to relieve Li Qiang and count this batch of books alone.

1/2÷4+1/x)*1=1-1/2

Then solve it yourself.

Option B is because the high-speed rail in the question is fixed, so it is stationary relative to the wind tunnel and the ground, and because it is a simulation experiment, its relative wind is moving.

Because the train model is fixed in the wind tunnel when the wind tunnel test is carried out, at this time, they are stationary relative to the ground, and only the high-speed wind is moving, so the high-speed rail train model is moving relative to the wind. I choose B

First of all, the correct answer is B. But can you tell me what your suspicions are? You have to figure out the doubts, and next time you do it yourself.

1.Take the surface of 8cm and 10cm as the bottom surface of Changrang, and the height of the sliding pin is 6cm, and the volume of the cone v=1 3*

2. 18cm³ 54cm³

3. 9cm³ 27cm³

In fact, the three points of examination are the same, that is, the volume of a cone is 1 3 of the volume of a cylinder of the same height as the bottom

From the known CN1+CN3+CN5+=128,2N 1=128,n=8, and the maximum term of the binomial coefficient in the formula is t4+1=c4 8 (x root number x) to the 4th power (1 3 root number x) 4 power = 70x43 root number x2．

Solution: 00,3-x>0,y=3x(3-x), 3 *[x+3-x) 2], 3*(9 4), 27 4

If and only if x=3-x, i.e., when the town is closed x=3 2, the equal sign is established.

So the maximum value of 3x(3-x) is 27 4 I hope mine helps you.

Quiz everyone: This is a math problem that can measure whether a person has business acumen.

Master Wang is selling fish, a pound of fish at a price of 45 yuan, now a big sale at a loss, the customer bought a kilogram for 35 yuan, gave Master Wang 100 yuan fake money, Master Wang has no change, so he asked a neighbor for 100 yuan. Afterwards, the neighbor found out that the money was fake in the process of depositing money, and it was confiscated by the bank, and Master Wang lost 100 yuan to the neighbor, how much did Master Wang lose in total?

Note: kg vs. kg.

A total loss of 100 + (45 2-35) = 100 + 55 = 155 yuan.

(a) f(z)=f +f z+f z +f z + zf(z)=f z+f z +f z +f z + 1-z)f(z)=f +(f -f)z+(f -f)z + i.e., (1-z)f(z)=0+(1-0)z+f z +f z + then (1-z)f(z)=z+z+z (f +f z+ ) i.e., (1-z)f(z)=z+z(z)(1-z-z)f(z)=z(z)f(z)=z, so f(z)=z(1-z-z). (b) an=19(f an +f an +f an +fn a )an =19(f an +f an +f an +fn a ) subtract the two formulas to obtain an-an =19(f an +f -f )an +f -f )an +fn -fn )a) i.e. an-an = 19 (0 + (1-0)an +f an +fn a ) i.e. an-an = 19an +19 (f an +fn a) i.e. an-an = 19an +an so an-an -20an = 0 i.e. an = an +20an (when n 2) In addition, a = 9, a = 19 (f a ) = 0 (c) an = an +20an a = 9a =0 then a = a +20a =0 + 20a = 20a a = a +20a =a +20 * 0 = a =20a a =20a = 20a +20a +20a +20a +20a +20a = 21 * 20a a = a +20a = 21 * 20a +20 * 20a = (21 + 20) 20a a = a +20a =(21+20)20a +20*21*20a =(20+21+20*21)20a a =a +20a =(20+21+20*21)20a +20(21+20)20a =(20+21+20*21+20(21+20))20a an=an +20an =a +20(an +an +an +a )

Tell me what the topic is.

My culture doesn't dare to do this.

A man can not be handsome, he can have no money, but he must be sassy.

If you are referring to the sound of the recording screen, you can go to the phone settings - Super Screenshot to turn on the screen recording sound.

Turn left|Turn right.

If there is anything you don't understand, you can ask at any time, I will try my best to answer, I wish you academic progress, thank you.

If the issue is resolved, click "Select as satisfactory answer" below