29D 2 18 Urgent A 6th grade Olympiad math problem

Let the time of the encounter be x

From the title, it is known that the trip of line B x takes 15 minutes for line A.

Then the velocity ratio of A and B is x:15

The journey of line A x takes 60 minutes for line B.

Then the velocity ratio of A and B is 60:x

Then x:15=60:x

x=30 means that the whole process of line A should be 30 + 15 = 45 points.

The whole process of line B should be 30 + 60 = 90 points.

The speed of car A is 1 45 1 90 2 times the acceleration of car B.

Method 2: Arithmetic methods.

From the inscription, it is known that when A completes the journey in 15 minutes after the encounter, B travels 15 60 = 1 4 of the original journey before the encounter. That is, the journey before the meeting of A is four times that of the 15-minute journey after the meeting of B.

It can also be concluded that A's journey before the encounter is twice as much as B's journey before the encounter. That is, when they meet, A has done 2 3 of the whole process, and B has gone 1 3 of the whole process

Then the completion of line A takes 15 [1 3] = 45 points.

The completion of line B takes 60 [2 3] = 90 points.

The speed of car A is 1 45 1 90 2 times the acceleration of car B.

Let the velocity of A be x and the velocity of B be yThe time of the encounter is t

According to the title: tx y=1

ty x=Treat x y as a whole and solve the equation to get x y=2 so the speed of car A is twice the speed of car B.

57 + 24 = 81, first 57 + 20 = 77, then 77 + 4 = 81;

91-29 = 62, 91-9 = 82 first, and then 82-20 = 62

So the answer is: 81; 57+20=77；77+4=81；62；Stuffy oak 91-9=82;82-20=62 Sophora panicle.

1、a=3√2，b=3√2

ab = (3 grinding macro2) +3 2) =36ab=62, oa=ob, then blind book b= opb=45°pod= bop

pod∽△bpo

op/od=ob/op

op²=3√2 od

Do pe ob in e, po = pd

Then oe=de=1 2od, pe=be=ob-oe=3 2 -1 2od

op²=pe²+oe²

3√2 od=(1/2od)²+3√2 -1/2od)²3√2 od=1/4 od² +18 -3√2 od +1/4 od²

1/2od² -6√2od +18=0

od²-12√2od +36=0

od=(12√2 ±12)/2

od=6√2 ±6

od=6 2 +6 (rounded).

d coordinates (6 2 -6,0) take rough.

26. Solution:

Original = 6 + 10 + 2 3

27. Solution: original formula = 7-13+3

328, solution:

Original = 1 3 + 1 4

29. Solution: original formula = 1 3 + 2 3