Xiaoming is 142 cm tall, a cm shorter than Xiaohua, and Xiaohua is () cm tall

Xiaoming is 142 cm tall, a cm shorter than Xiaohua, and Xiaohua is () cm tall

142 + a CM

Xiaoli is 1.37 meters tall, 0.08 meters shorter than Xiaojun, and Xiaojun is 0.03 meters shorter than Xiaoming. What's Xiaoming's height? (mixed decimal addition and subtraction)

1.37+0.08+0.03

They are ranked in the order of height from high to low. Xiaoming is 143 cm, Xiaoli is 1.15 m, Xiaohong is 13.8 decimeters, Xiaojun is 140 cm,
The answer is 143 cm 140 cm 13.8 decimeter 1.15 meter or Xiaoming Xiaojun Xiaohong Xiaoli

143 cm 140 cm 13.8 decim 1.15 M

A and B can meet each other in 8 hours from ab. a can travel less than 1 kilometer per hour, B can travel more than 3 kilometers per hour, and meet each other in 7 hours. The distance between a and B is less than 1 kilometer

Let the unknown distance between the two places be X
The first velocity of a is a
The first velocity of B is B
Then:
8(a+b)=X
The second velocity of a is A-1
The second velocity of B is B + 3
Then:
7(a-1)+7(b+3)=X
The results are as follows
X = 112 km

[(1+2^-(1/32)]*[(1+2^-(1/16)]*[(1+2^-(1/8)]*[(1+2^-(1/4)]*[(1+2^-(1/2)]

[(1+2^-(1/32)]*[(1+2^-(1/16)]*[(1+2^-(1/8)]*[(1+2^-(1/4)]*[(1+2^-(1/2)]
=[(1-2^-(1/32)]*[(1+2^-(1/32)]*[(1+2^-(1/16)]*[(1+2^-(1/8)]*[(1+2^-(1/4)]*[(1+2^-(1/2)]/[(1-2^-(1/32)]
=[1-2^(-1)]/[(1-2^-(1/32)]
=1/[(2-2^(31/32)]

On a map with a scale of 1:2000000, the distance between a and B is measured to be 10cm. If we change it to a map with a scale of 1 / 5000000
How many centimeters should be drawn on the picture?

On a 1:2000000 map, the distance between a and B is 10cm
Represents the actual length = 10 cm * 2000000 = 20000000 cm = 200 km
On a 1 / 5 million scale map,
Length to be drawn = 200 km * 1 / 5000000 = 20000000 cm * 1 / 5000000 = 4cm
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If nonzero real numbers a and B satisfy 4 times the square of a plus the square of B = 4AB, then a divided by B =?

Because 4A ^ 2 + B ^ 2 = 4AB, that is, (2a-b) ^ 2 = 0, so 2a-b = 0, 2A = B, so a / b = 1 / 2

If the number of a is 0.8 more than that of B, and the number of a: B = 7:5, can you find out the number of a?

A: the number of a is 2.8

Mean inequality proof problem! It's not difficult, but I can't
If we know a > b > C, we can prove that 1 / (a-b) + 1 / (B-C) is greater than or equal to 4 / (A-C)

Certification:
The original inequality is equivalent to prove (A-C) / (a-b) + (A-C) / (B-C) > = 4
Note that (A-C) / (a-b) = (a-b + B-C) / (a-b) = 1 + (B-C) / (a-b)
(a-c)/(b-c)=(a+b-c-b)/(b-c)=(a-b)/(b-c)+1
So (A-C) / (a-b) + (A-C) / (B-C) = 2 + (B-C) / (a-b) + (a-b) / (B-C)
Because a > b > C, B-C and A-B are positive numbers
(b-c)/(a-b)+(a-b)/(b-c)>=2
Then (A-C) / (a-b) + (A-C) / (B-C) > = 4
At the end of the examination

The two trains a and B start from a and B at the same time and run in opposite directions. After 1.5 hours, they meet at 18 kilometers away from the midpoint. It is known that the speed of train a is 1.2 times that of train B. how many kilometers did the two trains travel when they met?

18 × 2 △ 1.5 △ 1.2-1 = 24 △ 0.2, = 120 (km). 120 × 1.2 = 144 (km). 120 × 1.5 = 180 (km). 144 × 1.5 = 216 (km)