Arrange the positive and even numbers into 5 columns as follows: column 1, column 2, column 3, column 4, column 5, row 1, row 2, row 2, row 16, 14, 12, 10, row 3, row 2, 30, 28, 26 According to the above arrangement, 2012 should be ranked in () A. Line 502, column 1 B. line 250, column 5 C. line 251, column 4 d. line 252, column 3

∵ 2012 is the 1006th item in the positive even sequence, and ∵ four items in each row, ∵ the second number in the 252nd row. The 252nd row is from left to right and starts from the second row, ∵ 2012 is the third column in the 252nd row. So select D

The following scientific counting method is incorrect ()
A. 1230.45 ≈ 1.2 × 10 3 (keep two significant numbers)
B. 1230.45 ≈ 1.23 × 10 3 (accurate to ten)
C. 1230.45 ≈ 0.1 × 10 4 (accurate to 10000 bits)
D. 1.65 × 10 3 ≈ 1.7 × 10 3 (accurate to hundreds)
10 (3) is the third power of 10
10 (4) is the fourth power of 10
Add a question: how to keep two significant numbers in 2563

c
It should be accurate to thousands
2.6×10③

Approximate numbers and significant numbers in mathematics volume 2 of Grade 7
At present, a cup of 10% sugar water solution is 10ml. Pour out 10ml of the solution for the first time and then fill it with water. After fully mixing, form a new sugar water solution of 100ml. Pour out 10ml of the solution for the second time and then fill it with water. After fully mixing, form a new sugar water solution After the first and second operation, how many ml sugar are left in the solution? What is the concentration of the solution?

Rain and snow,
First pour out sugar: 10 × 10% = 1 (ML)
At this time, the residual sugar in the solution: 100 × 10% - 1 = 9 (ML)
After adding water, the sugar content is: 9 △ 100 = 9%
The second time: 10 × 9% = 0.9 (ML)
At this time, the residual sugar in the solution: 100 × 9% - 0.9 = 8.1 (ML)
Sugar content after adding water: 8.1 △ 100 = 8.1%

Given that a and B are positive integers, and the square of a minus the square of B is equal to 45, find the value of a and B

Square a minus square B equals 45
（a+b）（a-b）=45
45=1*45=3*15=5*9
A = 23, B = 22 or a = 9, B = 6 or a = 7, B = 2
A = (45 + 1) / 2 or a = (15 + 3) / 2 or a = (9 + 5) / 2;
B = (45-1) / 2 or B = (15-3) / 2 or B = (9-5) / 2

Given that a and B are positive integers, and satisfy that the square of a minus the square of B is equal to 2007, find the value of a and B

a=1004,b=1003

If the negative quarter times the cube of x times the 2n power of Y is a quintic monomial, do you know what n is

If the 2nth power of the negative quarter times the cube of x times y is a quintic monomial, n = 1

Please write all trinomials that contain only the letter x.y with a coefficient of 2

2x^2y
2xy^2

Write out all the quintic monomials with coefficient - 1 and only x and Y letters

-X ^ 4Y, - x ^ 3Y ^ 2, - x ^ 2Y ^ 3, - XY ^ 4

Write out all the quintic monomials with coefficients of - 1, all of which contain the letters X and y, but not other letters
Just write it down~

-xy^4 -x^2y^3 -x^3y^2 -x^4y

Please write two different monomials, one is 1, the other is - 1, the letters are x and y, and their times are 3

X squared y
-XY squared