Linear algebra often says n-order matrix, what does this "order" mean? M or n? Of a matrix whose rank is m times n?

Order is generally used in the case of square matrix, M = n, which means that m or N, non square matrix has no order
Rank is smaller than order

Finding a ^ 4 =?
The known matrix A = 1 1 - 1
-1 -1 1
1 1 -1
Find a ^ 4 (which is the fourth power of a)

Set
b =
one
-1
one
c = (1,1,-1),
Then a = BC, a ^ 4 = (BC) (BC) (BC) (BC) = B (CB) (CB) C = B (CB) ^ 3C
And CB = - 1, so a ^ 4 = B (- 1) ^ 3C = - BC = - A=
-1 -1 1
1 1 -1
-1 -1 1

The difference between the two squares is 3cm in length and 45cm in area. How much is the sum of the two squares?
As long as the formula is typed with the symbols + - ×, otherwise I can't understand it

Side length of small square: (45 △ 3-3) △ 2
=（15-3）÷2
=6 (CM)
Side length of large square: 6 + 3 = 9 (CM)
Sum of area: 9 × 9 + 6 × 6 = 81 + 36 = 117 (square centimeter)

The revolution of the moon and the revolution of the earth
It's better to state the direction of rotation accurately,

The cycle of the earth's revolution is called a solar year, which is about 365 days, 4 hours, 58 minutes and 56 seconds. The direction is from west to East
The earth's rotation is from west to East. The average angular velocity of the earth's rotation is 7.292 × 10-5 radians per second, and the linear velocity of the earth's rotation on the equator is 465 meters per second. Generally speaking, the earth's rotation is uniform. However, precise astronomical observations show that there are three different variations in the earth's rotation. The earth's rotation takes 23 hours and 56 minutes, The rotation cycle increases or decreases by three to four thousandths of a second every 10 years
The movement of the moon is from west to East. The evidence of the moon's westward movement is that the time of each sinking is delayed by 49 minutes on average

Conditions for the existence of three stress components in plane problems

The plane stress problem has only x, Y direction stress and XY shear strain, but no thickness direction (z direction stress),
The plane strain problem is x-normal strain, y-normal strain, XY shear strain. In addition, the z-direction (axial) stress is generally not 0 (because the axial expansion is prevented, if not, it is 0)

It is known that the perimeter of a square is LCM and the area is s square centimeter. (1) find the function expression between S and L. (2) how does s increase with l

Side length L / 4
So s = L & # / 16
Because l > 0
So s increases with L

Simple calculation of 0.87 * 2.5 + 8.7 * 7.5

=8.7*2.5/10+8.7*7.5
=8.7*(0.25+7.5)
=8.7*7.75
=64.425

Let u = R, f (x) = √ (1-x) + √ (x + 2) be defined as a, and G (x) = x ^ 2-2x-3 be defined as B. find the complement intersection B of A

To make f (x) meaningful, then:
1-x > = 0 and X + 2 > = 0
2

A rectangle is 20 cm long and 120 m wide. If you subtract the square with the side length of 2 cm from its four corners, the perimeter of the remaining figure will be smaller than the original one
(), the original ratio of area ()
A increases b decreases C unchanged D cannot be determined

A rectangle is 20 cm long and 120 m wide. If the square with 2 cm side length is subtracted from each of its four corners, then the perimeter of the remaining figure and the original ratio (c) remain unchanged, and the original ratio (b) of the area decrease

Use four arithmetic operations to make three 5's and one 1's into 24? (you can use brackets to change positions at will)
This is a very simple topic, don't think so much/

5*(5-1/5)=24

Linear algebra often says n-order matrix, what does this "order" mean? M or n? Of a matrix whose rank is m times n?