The number of 45 ones and 45 thousandths is ()

The number of 45 ones and 45 thousandths is ()

Well, I'm sorry to answer
In fact, this is the most basic. You really have to do it yourself

I have a math problem, I don't know whether it's right or wrong
PI is the ratio of circumference to straight meridian (). Should this question be checked or crossed?
I think it should be wrong. In my opinion, the last word of "Pi" should be changed to "ratio". Is my idea right? Should this question be checked or crossed?

I don't think it's right. It doesn't say "in the same circle". Only the circumference of the same circle is π times the diameter!
I'm in sixth grade

How to arrange 1, 1, 2, 2, 3, 3, 4, 4 so that there is one other number between two 1s; two other numbers between two 2S; three other numbers between two 3S; for example, 312132, 231213; whether there are four other numbers between two 4S? At least two sets of answers are required

23421314
forty-one million three hundred and twelve thousand four hundred and thirty-two

A and B walk in the opposite direction at the same time from two places 200 meters apart. A travels 65 meters per minute and B 70 meters per minute. After 8 minutes, how many meters is the distance between them?

(65 + 70) * 8 + 200 = 1280 or (65 + 70) * 8-200 = 880

Mathematics one variable quadratic equation
For the sake of urban appearance and greening environment, after two years, the green area of a city has increased by 44%. How about the average annual growth rate of green area in these two years?

Setting: the average annual growth rate of green space area in the past two years is X
Then: (1 + x) &# 178; = 1.44
∴1+x=±1.2
∴x1=0.2=20％
X2 = - 2.2
The average annual growth rate of green space area in the past two years: 20%

220（1+x）（1+x）=242

（1+x）（1+x）=242/220
（1+x）²=242/220
1+x=√242/220
X = ± √ 1.1 (1.1 is 11 / 10, understand) - 1
x=[ ±√（11×10）/（10×10） ]-1
x=±1/10√110-1
X1=1/10√110-1
X2 = - 1 / 10 √ 110-1 is detailed enough

Ninth grade mathematics, with a quadratic equation solution
It is necessary to use 20 meters long iron railings, one side against the wall, to form a rectangular flower garden. How to make the largest area of the flower garden? It is best to give a method. If you can answer it, I will be very grateful

Let the length of the side against the wall be x, then the width is (20-x) / 2
So the area is s = x (20-x) /. 2 = - 1 / 2 (X-10) & 178; + 50
So when x = 10
The maximum area is 50 square meters
So it's 10 meters long and 5 meters wide

64+（ ）=64-（ ）

0,64-0 = 64 + 0

How much is 150 minus 99

150-99 = 150-100 + 1 = 51, so 150 minus 51 equals 99

How much is infinity minus infinity? Why?
How much is infinity plus infinity? Why? Then how about subtraction, multiplication, division, power and square root? Why?
I can understand the situation except subtraction. I think the answer is infinite. Why
I'm a freshman in high school, but I've learned the derivative part. I hope I don't talk too much about it!

If you have learned derivative by yourself, then you should have a certain understanding of limit theory (taking the theory of ε - n as an example). The operation of infinity (that is, the so-called "infinity" in the textbook) depends on the specific way of function / sequence divergence, which cannot be generalized