It s two math puzzles, ask the experts to help

The first question is very simple, in the ratio, the product of the two internal terms is equal to the product of the two external terms, and the two internal terms are the reciprocal of each other, that is, the product is equal to 1, then the product of the two external terms is of course equal to 1, that is to say, one external term is 1 15, and the other external term is 15. For example, 1 15:1 5=5:

15 In the second question, first of all, the difference can be set to x, then the subtraction is 3x (because the ratio of the difference to the subtraction is 1:3), and the subtraction is 4x (the subtraction - the subtraction = the difference);

So, 4x+3x+x=80 solves the equation and obtains, x=10, so the subtraction is 40, the subtraction is 30, and the difference is 10

1.The answer is 15

Reasony=15(x*1) x=15

2.Let the subtraction be a, the subtraction be b, and the difference be c

According to the question, it can be obtained: a-b=c c=b 3 a+b+c=80a=b+c=4b 3 then: 80 (4 3 1 1 3)bSo: b=30 c=10 a=40

1.The answer is 15, in the ratio, the product of the two internal terms is equal to the product of the two external terms, and the two internal terms are the reciprocal of each other, that is, the product is equal to 1, then the product of the two external terms is of course equal to 1, that is to say, one external term is 1 15, and the other external term is 15. For example, 1-15:

or y=15(x*1) x=15

2.Let the difference be x, then the subtraction is 3x, and the subtraction is 4x4x+3x+x=80 Solve the equation, and the subtraction of x=10 is 40, the subtraction is 30, and the difference is 10

1. Proof: pass D as DH perpendicular to BC, and hand over BC at point H.

Then DH=AB=AF, because AF BC, hcd= CDF

Because cdf= AEF

So hcd= aef

And because eaf= chd=90°

So the triangle DHC is congruent with the triangle FAE.

So ef=cd

The diagram is too small, and the proof question should not be typed up, and the format is very particular.

The one closest to 1 90 can only be 1 100.

This function is above the line y=-a and the smaller x is closer and closer, and 1 (x-1) is also closer to x smaller and closer below y=0.

So just -a<0, which is a>0.

x] is a Gaussian integer function.

10-3 hours.

Because according to the average speed of A, B and C, it takes 5 hours for two people to join together.

The three-person union is 1 2:5=1 3:x x=10 3 hours, i.e.

Let x1 x2 x3 be the typing rate of A, B, C.

There is 4(x1+x2)=5(x2+x3)=6(x1+x3) to get x1=0

x2=0x3=0

Looks like there's something wrong with this question.

Just turn this answer upside down 2 1 4 1 5 1 6 hours.

That is, you don't seem to have a clear topic.

I think it is possible to solve a system of equations as:

t A + t B = 4

t B + t C = 5

T A + T C = 4

Solve this system of equations.

tA = hour t B = hour t C = hour So the three of them played a total of hours, this answer is for reference.

There is a manuscript, A and B spent 4 hours together, B and C worked for 5 hours, A and C played for 6 hours, how many hours did the three of them play in total?

Answer: A completes x in one hour, B is y, and C is z. The file size is k, and it is known: x+y=k 4

y+z=k/5

x+z=k/6

Yields: 2(x+y+z)=37k 60

Solution: x+y+z=120 37 hours.

A can't be between 3-4, B can't be 5-4, C can't be 4-6

The system of column equations is as follows:

A + B = 1 4

B + C = 1 5

A + C = 1 6

Solve the equation to obtain: A = 13 120;B = 17 120;C = 7 120 So the total time of the three people is: 1 (13 120 + 17 120 + 7 120) = 120 37

A completes x in one hour, B is y, and C is z. The file size is a, what is the problem?

Known: x+y=a 4

y+z=a/5

x+z=a/6

Yields: 2(x+y+z)=37a 60

Solve: x+y+z=a ?

Join to solve, x+y+z is gone, a is gone, is eliminated? = 120 37 hours.

A+B Hour to complete the total 1 4

B + C Complete a total of 1 5 per hour

A+C Completes the total 1 6 per hour

A + B) + (B + C) + (A + C) = 1 4 + 1 5 + 1 6 That is: A + B + C Completed per hour Total (1 4 + 1 5 + 1 6) 2 The time shared by the three people: 2 (1 4 + 1 5 + 1 6 ) hours.

A, B, C, 16 hours were shared.

（1/4＋1/5＋1/6﹚÷2＝37/120

1 37 120 120 37 hours 3 and 9 37 hours.

I don't know, right? Ask for adoption!

Your derivation is correct, these five are indeed roots, but not necessarily only five because with 3 as the period, it does not mean that 3 is its minimum positive period, if the minimum positive period is 1, then 3 can also be its period.

So the solution derived from the problem is not necessarily all of its solutions.

Ah, it's more tangled.

That's what I did.

Please take another look at the question, is there a mistake in the interval?

If the interval is [0,6], then the roots are 7.

Please take another look at the question.

From f(0)=0 pushes f(3)=0

From f(2)=0 f(5)=0, f(-1)=0, f(-4)=0, and then f(1)=f(-1)=0, f(4)=f(-4)=0, so f(1)=f(2)=f(3)=f(4)=f(5)=0, f(f( f(

So there are 7 of them.

Set car A to drive for x hours after departure, and the two cars are 100km apart Situation 1: A and B have not yet met.

72x 40( x - 25÷60) 100 = 36072x 40x - 50/3 100 = 360112x = 830/3

x = 415/158

Situation 2: The two cars have met.

72x 40( x - 25÷60) -100 = 36072x 40x - 50/3 - 100 = 360112x = 1430/3

x = 715/168

A: After 415 158 hours or 715 168 hours after departure, the two vehicles are 100 kilometers apart.

The volume of the pool: cubic meters).

Pipes are filled with water per second: cubic meters per second).

80% of the volume of the pool: cubic meters).

1.Water injection volume v1 = per minute

The volume to be injected into the pool v2 = 8 5

Time t=v1 v2 26 minutes.

2.Let the cost be a, based on the amount of money sold on the first day of the puppy as much as the second day, there is the equation: 98 (a+, solution: a=49

If a cylindrical pipe with a diameter of 20 cm is used to fill the pool with water at a speed of 4 m per second, then the amount of water injected per minute is: 80 of the water in the pool It takes about 8 5 1 80% ( minutes.

Let the cost be x yuan, then: (x + the amount of money is equal to the selling price multiplied by the quantity sold).

Solution: x=686

1. 20cm=2m divided by 2) squared x4=

60x80 = 48(m) 48 divided by approximately 4 minutes.

2. Assuming that the cost is a, based on the amount of money sold on the first day of the puppy and the amount of money sold on the second day, the equation can be obtained: 98 (a+, solution: a=49