4 out of 9 times 10 minus 4 out of 9 simple and convenient 129 times 127 out of 128 minus 127 times 1 and 1 out of 128

4 out of 9 times 10 minus 4 out of 9 simple and convenient 129 times 127 out of 128 minus 127 times 1 and 1 out of 128

4 out of 9 times 10 minus 4 out of 9
=4 / 9 times (10 minus 1)
=Four out of nine times nine
=4

A 20 decimeter long cuboid wood is sawed into two small cuboids along the high direction, and the surface area increases by 10 square decimeters. The volume of this wood is () cubic minutes
Write the answer directly

10 △ 2 = 5 (square decimeter) (calculate the area of a small cuboid first)
5 × 20 = 100 (cubic decimeter) (cross section multiplied by length)

75 = () divided by 16 = ()% = 27 parts () = 21: ()

9 75 36 28
The correct answer is expected to be adopted

N is a natural number, and n ^ 3 + 2005 can be divided by the natural number n + 25. What is the maximum of N

The minimum is: 1
Because there is no maximum

Put 29, 30, 31, 32, 33, 34, 35, 36, 37 in the space of 3 times 3 to make them all 99?

34、35、30
29、33、37
36、31、32

In (a + b) &# 178; = A & # 178; + 2Ab + B & # 178;, how to prove a & # 178; + B & # 178; ≥ 2Ab (except for examples) O (∩)_ Thank you
In (a + b) ² = A & #178; + 2Ab + B & #178
How to prove a & # 178; + B & # 178; ≥ 2Ab (except for example)

Is this too simple
a²+b²-2ab=（a-b)²
（a-b)²≧0
so a²+b²-2ab≧0 =>a²+b²≧2ab

Fill 1, 2, 3, 4, 5, 6, 7, 8, 9 into the three grids horizontally and vertically, so that the sum of the diagonal numbers of each row and column is equal
If it's convenient, please talk about the practice of this kind of problem

492
three hundred and fifty-seven
eight hundred and sixteen
Yes, there are ways
Reference method: magic cube matrix
The numbers follow the order from small to large. They can be 1 to 9. They can also be - 1 to 7, - 2 to 6
It can also be enlarged or reduced by a certain multiple, such as - 15, - 12, - 9, - 6, - 3,0,3,6,9
Look at this method. You're trying a 1-81 9 * 9 grid, isn't it easy?

2X + 4Y + Z = 9 x + y + 2Z = 5 4x + 2y-z = 7 to solve the linear equation of three variables

2x+4y+z=9.1
x+y+2z=5 .2
4x+2y-z=7.3
1 + 3
6x+6y=16
3x+3y=8.4
2 + 3 * 2
9x+5y=19.5
Formula 4 * formula 3-5
4y=5
y=5/4
Put it into formula 4
3x+3*5/4=8
3x=17/4
x=17/12
4x+2y-z=7
4*17/12+2*5/4-z=7
49/6-z=7
z=7/6
So x = 17 / 12, y = 5 / 4, z = 7 / 6

All the answers of the fifth grade volume I of the supplementary exercises of Mathematics

Children, you have to type out the questions first. If you don't type out, how can I know the answer? It's better to use your own brain to think. I believe you will be more and more intelligent,

In the square - 7x + 3 of the algebraic formula MX, when x = - 2, the value of M is 25

Substitute x = - 2 to get: 4m + 14 + 3 = 25
So 4m = 8, that is, M = 2