Pls 0 math question 0 answer, math question about 0

Profit and loss issues.

All are calculated according to the scheduled time.

Walking 50 meters per minute, you can walk more: 50 3 = 150 meters.

40 meters per minute, less: 40 2 = 80 meters.

Difference: 150 + 80 = 230 meters.

Difference per minute: 50-40 = 10 meters.

Scheduled time: 230 10 = 23 minutes.

Distance from home to school: 50 (23-3)=1000 meters.

Set the distance from home to school x meters.

then x 50 + 3 = x 40-2

x=1000

It takes t t to get from home to school.

Then: 50(t-3)=40(t+2) t=23

23-3)*50=1000 meters.

If the distance from home to school is x, then x 50 + 3 = x 40-2

4x+600=5x-400

x=1000

The distance is 1000 meters.

The distance from the home road school is x

The equation x 50 = a-3 and x 40 = a+2 can be obtained x = 1000

Let the distance be x, then x 50 + 3 = x 40-2

Solution x = 1000 meters.

It is 1000 meters from home to school.

It's rare for you to think about these questions, top.

There is such a provision in the mathematical law, and then you understand the concept of the first congratulatory method, for example, dividing by 1 is dividing one part by dividing 2 is dividing by 2 parts, divided by 0, how many parts of the vernal equinox are called?

LZ is very studious! Hehe, see if you agree with my answer?

In the teaching of "Understanding Multiplication and Division", for the provision that "0 cannot be used as a divisor", it is often said that "it is meaningless to make a divisor for zero" or "it is stipulated that zero cannot be a divisor", and many teachers often just treat it as a conclusion, emphasizing that "0 is meaningless to do a divisor". In fact, this is an excellent example of guessing the "multiplication and division relationship". "Why can't zero be a divisor"?

This can be said in two ways:

1. When the dividend is zero, and the divisor is also zero, we can write it in the form of 0 0 0=x, and what is the quotient x? According to the relationship between multiplication and division, which are inverse operations with each other, there is: dividend = divisor quotient, where the divisor is zero, and quotient x is equal to zero no matter what number it is (it is a positive number, a negative number, zero), and multiplying it with zero.

i.e. 0=0 x, so that the quotient x is not fixed. x is any number multiplied by zero to be equal to zero. We know that the results of the four operations are unique, which destroys the uniqueness of the results of the four operations.

In this case, we simply say, "When both the dividend and the divisor are zero, we cannot get a fixed quotient." ”

2. When the dividend is not zero, and the result when the divisor is zero, we can write 5 0=x, and the quotient x, no matter what the number, multiply it with the divisor "0" to get zero, and not 5, that is, 0 x≠5 or other numbers that are not zero. Let's simply say, "When the dividend is zero and the divisor is zero, the relationship between multiplication and division is 'not going back to the original'".

Therefore, "0" cannot appear as a divisor in the 4 operations.

In view of the above two situations, the source situation is simplified: one is that zero is a divisor and cannot get a fixed quotient; The second is that zero is not the divisor and does not return to the original. Therefore, it is said: "It does not make sense for zero to be a divisor" or "It is stipulated that zero cannot be a divisor".

I'm math, so as not to mislead you here, now give the correct answer:

The quadratic of 0 has the meaning of Lu Hong, 0 = 0

A zero power of 0 doesn't make sense. (See the accompaniment and the next supplement:) zero can be used as a prescription for the omen. √0

First, it is judged that a>2009, if not, the absolute value is removed, and it is reduced to 2a- a+1=0, and a has no solution.

a>2009, it is a-2010=2009. The value is 2010 +2*2010*2009.

If the unit price of pears is x yuan kg, then the unit price of apples is yuan kg;

The weight of the pear is 30 (x) and the weight of the apple is 30 (.

Apples are kilograms lighter than pears, 30 (x)-30 (

Solve this equation to get: x=4, so.

The unit price of pears is 4 yuan kg, so the unit price of apples is 6 yuan kg.

First of all, I would like to give you a thought, the speed at which sound travels through the air is constant, so no matter how fast the car drives, the speed of sound is still 340m s, which is the nature of waves, so the solution to this problem is.

72km/h=20m/s

The time it took to hear the sound was 4s away, and the distance was: s=340*4=1360m

The distance of the car is: s=20*40=80m

72km/h=20m/s

The distance of the car from the valley when the echo is heard s = (20m s * 4s + 340m s * 4s) 2 - 20m s * 4s = 640m

The distance traveled by car l = 20m s * 4s = 80m The distance traveled by sound line x = 340m s * 4s = 1360m

72 km/h = 20 m/s.

Distance from the valley by car:

340 + 20) * 4 2 = 1520 meters.

The distance traveled by the car:

20*4=80 meters.

Sound Travel:

340*4=1360 meters.

72 meters per second.

It turns out that the distance between the car and the valley (20 + 340) * 4 2 = 720 meters is heard after 4 seconds, when the echo is heard, the distance is 720-20 * 4 = 640 meters, and the car travels 20 * 4 = 80 meters.

Sound travel 340*4=1360 meters.

Analysis: The car was driving for 4 seconds when an echo was heard. Since the speed of the car is 72 kilometers per hour, the distance traveled by the car is the distance of the car from the valley.

And because the propagation speed of sound is 340 meters per second, the time from honking the horn to hearing the echo is 4 seconds, indicating that the sound travels for 4 seconds, so the stroke of the sound is 4*340

Solution: There are x1 prizes.

200x+50（22-x）=1400

200x+1100-50x=1400

150x=300

x=2A: There are 2 winners of the 1st prize.

If the first prize is set for x people, the second prize will be 22-x people.

200*x+50*（22-x）=1400

150*x+1100=1400x=2

According to the root finding formula, the trace nucleus is sold. x1=b

b 2-4ac)) 2ax2=-b(b 2-4ac)).

2a wants to subtract and add the absolute comma value is the above conclusion.

Untie. Since the point (0,-3) is on the ellipse.

So b 2 = 9

Eccentricity e=ca=32

So we get 3a=2c, i.e., 3a 2=4c 2, and according to the ellipse relation, we get:

3a^2=4（a^2-b^2）

i.e., 36 = a 2

In summary, the elliptic equation is (x 2 36) + (y 2 9) = 1 solution. Let lab:y=kx+b because the intersection of lab and the ellipse is symmetrical with respect to the known straight lines.

That is, "the midpoint of the two intersections is on a known line" and "the known line is a perpendicular line of lab".

From this, it can be seen that Lab is perpendicular to y=2x-6, so k=-1 2 simultaneous y=(-1 2)x+b and the elliptic equation are obtained.

x 2-2bx+2b 2=36, according to Veda's theorem there is:

x1+x2=-b a=2b, that is, the abscissa of the coordinates of the midpoint of the two intersections is x=(x1+x2) 2=b

Bringing x=b into y=2x-6 gives y=2b-6, which is the ordinate of the midpoint of the two intersections.

Bring the dots (b, 2b-6) into the lab, getting.

2b-6=(-1 2)b, the solution is b=12 5 in summary, y=(-1 2)x+(12 5) is what is sought.