It s a super hard math problem

6) Let half of the distance be s

Since the time is equal, (s+1) 5 = (s-1) 4 solves s=9 and the distance is 18km'

7) Let the distance be s, the speed of A is x, and the speed of B is y

Let's start with the first equation, which is based on the fact that whoever adds five to the last two times adds velocity, and these two times are equal to the velocity.

So it takes the same amount of time, but the last two times are faster than the first, how much faster, if you use Nirci's.

That is, 12 x is used less, and the third time is 16 y less, from the analysis just 12 x = 16 y

That's the first equation that works.

Let's talk about the second equation, which is based on the time taken by 6 hours, s = 6 * x + y).

The third equation can be based on any time when the last two times are less than the first.

I'll pick it a second time S (x+y) -s (x+y+5) = 12 x

From the above three equations, s can be solved naturally

8) The first question: First of all, it is necessary to make it clear that both of them are going downhill, oh, well, let's see who is going to hurry up and hurry him.

It took 1 6 hours to use 5 12 hours for Wang to finish walking the slope and saw that Zhang had already walked 1km on the flat land.

After calculating the last 2km divided by 4*2 = 1 4, it took 2 3 hours in the end.

Second question: You have to budget the two of them from the point where they met, which is 2km away from B.

One calculation turned out to be Wang Kuai (first calculated the king, he took 1 hour, and then looked at Zhang's equation There is a number greater than 1).

So after 1 hour, it's OK to calculate where Zhang is Calculate the original Zhang is still 1km away from the end point

9) Question 1: Set the tension speed to x (x+180) *75 60 = 500 (Note.)

Unified unit) Calculate x=220m min

Question 2: Find the speed difference 220 - 180 = 40

500 divided by 40 = 25 2

Knowing the time it took to catch up with him, the distance in the calculation = 220 * 25 2

2750m So it took 5 and a half laps to catch up.

10) This calculation may require solving quadratic equations, I don't know if you have learned the details I wrote.

Or is it an equation of equality in time, let the tensile velocity be x, the king velocity be y, and half of the circumference is s

80/x = (s-80) / y

80+s-60)/y = (s-80+60)/x

Divide by one and two to eliminate xy

Get the quadratic equation about s: s 2 - 180s = 0

s(s-180)=0

s cannot be 0 so s = 180 meters.

6.The distance between A and B x

x/2+1)/5=(x/2-1)/4

4x+8=5x-10x=18