How does matlab define an empty matrix with a certain number of rows and columns to store the array,

How does matlab define an empty matrix with a certain number of rows and columns to store the array,

An empty matrix has no size. You can fill it as much as you want
For example:
>> m=[]
m =
[]
>> a=zeros(3);
>> m=a
m =
0 0 0
0 0 0
0 0 0

Who can tell me how to read and use these mathematical symbols?
≡
≠
≮
∷
∫
∮
∝
∞
∧
∑
∏
∪
∈
∵
⊥
‖
∠
⌒
⊙
≌
∽
√
≤
≈
≡
∟
⊿
㏒
㏑
¤
I understand what they mean, but what's the pronunciation? Hee hee

Equal to
Not equal to
Not less than
……
integral
Curve integral (of closed path)
relevant
Infinity
And (logical and or intersection operation)
Sigma (for sum in Mathematics)
send
and
belong to
because
vertical
parallel
angle
arc
circular
Congruent
Radical
Greater than or equal to
be similar
……
Coincidence (in probability)
……
……
Lo Ge
㏑ (same as above, pronounced directly in English)
……
You are too strong. How can you type these symbols!

The mass of a pile of 2m3 concrete is 4.34 × 103kg, and the density of this pile of concrete is______ If 34 is used, what is the quality of the remaining concrete______ Kg, the volume is______ M3, the density is______ ．

The density of concrete is: ρ = MV = 4.34 × 103kg2m3 = 2.17 × 103kg / m3; after using 34, the mass of the remaining concrete becomes the original 14, and the density remains unchanged, then M = 14m = 14 × 4.34 × 103kg = 1.085 × 103kg, Volume V = M = M = ρ = 1.085 × 103kg, 2.17 × 103kg / m3 = 0.5m3

The form of square difference and factorization
1.x^4-3x^2y^2+y^4
2.64x^4+1

1.x^4-3x^2y^2+y^4=x^4-2x^2y^2+y^4-x^2y^2=(x^2-y^2)^2-x^2y^2=(x^2-y^2+xy)(x^2-y^2-xy)2.64x^4+1=64x^4+16x^2+1-16x^2=(8x^2+1)-16x^2=(8x^2+1+4x)(8x^2+1-4x)

Given that the vertex of the parabola y = 2x & sup2; + BX + 2 is on the number axis, find the value of B

y=2x²+bx+2=2(x+b/4)²+2-b²/8
If the vertex is on the X axis:
2-b²/8=0
b=±4
If the vertex is on the Y axis:
-b/4=0
b=0
∴b=0,b=±4

A student is doing the experiment of measuring the mass and density of liquid. If there is 100ml water in the measuring cylinder, the mass of water is______ 10 g of salt is put into the vector cylinder, and the mass of the salt is reduced when the salt is completely dissolved______ (fill in "larger", "smaller" or "unchanged"), then the density of the liquid in the measuring cylinder______ (fill in ">", "<" or "=") the density of water

① ∵ ρ = MV, ∵ the mass of water is m = ρ v = 1.0g/cm3 × 100cm3 = 100g = 0.1kg; ② put 10g salt into the vector cylinder, and the state of salt changes, but the mass is not related to the state, then the mass of salt remains unchanged; ③ the density of salt is greater than that of water, and after salt dissolves in water, the density of salt is between the density of salt and water, so it is greater than that of water 1. Unchanged

Finding the general term formula of the sequence 11101100110001 and the sum of the first n terms

An has n + 1 digits, the highest and individual digits are 1, and the rest are 0
an=10ⁿ+1
Sn=a1+a2+...+an
=(10+100+...+10ⁿ)+n
=10×(10ⁿ-1)/(10-1) +n
=10^(n+1) /9 +n -10/9

It is known that the parabola y = ax & # 178; + 2 intersects the x-axis at two points a and B. the parabola y '= a'x & # 178; + C' and y = ax & # 178; + 2 are symmetric about the x-axis
If the vertices of two parabolas are C and C ', and the area of quadrilateral ACBC' is 12, find the value of A

a=-9/2

Find a 45 steel cylinder, which is solid, 55 mm high and 300 mm in diameter?

I sell 45 round steel. In the steel market, the meter weight of round steel is kg = D & # 178; * 0.00617 (D is diameter mm), so the meter weight of this round steel is 300 * 300 * 0.00617 = 555.3kg, the length 55mm, and the weight is 555.3 * 0.055 = 30.5415kg
In addition, the density of ordinary steel is 7.85g/cm and 179;

A simple algorithm of 56 times 36

56*36=50*36+6*36=50*30+50*6+6*30+6*6=1500+300+180+36=1800+216=2016