About 500 words of mathematics essay in grade one of junior high school Relatively complete, 500-600 fast

About 500 words of mathematics essay in grade one of junior high school Relatively complete, 500-600 fast

On the floor or wall paved with ceramic tiles, the adjacent floor tiles or ceramic tiles are flat and close together, and there is no gap on the whole floor or wall
For example, triangles. Triangles are planar figures composed of three line segments which are not on the same line. Through experiments and research, we know that the sum of the internal angles of triangles is 180 degrees, and the sum of the external angles is 360 degrees. Six regular triangles can cover the ground
Let's look at the regular quadrilateral. It can be divided into two triangles. The sum of the internal angles is 360 degrees. The degree of an internal angle is 90 degrees and the sum of the external angles is 360 degrees
What about a Pentagon? It can be divided into three triangles. The sum of the internal angles is 540 degrees. The degree of an internal angle is 108 degrees, and the sum of the external angles is 360 degrees. It can't cover the ground
Hexagon, it can be divided into four triangles, the sum of internal angles is 720 degrees, the degree of an internal angle is 120 degrees, and the sum of external angles is 360 degrees
It can be divided into five triangles, the sum of the inner angles is 900 degrees, the degree of an inner angle is 900 / 7 degrees, and the sum of the outer angles is 360 degrees
From this, we get that. N-polygon can be divided into (n-2) triangles, the sum of internal angles is (n-2) * 180 degrees, the degree of an internal angle is (n-2) * 180 ／ 2 degrees, and the sum of external angles is 360 degrees. If (n-2) * 180 ／ 2 can divide 360, then it can be used to cover the ground, if not, it cannot be used to cover the ground
We can not only use one regular polygon to cover the ground, but also use two, three and more graphics to cover the ground
For example: regular triangle and square, regular triangle and hexagon, square and regular octagon, regular pentagon and regular octagon, regular triangle and square and regular hexagon
In real life, we have seen a variety of patterns made of regular polygons. In fact, many patterns are often made of irregular basic graphics

The method of quoting common factor in the second volume of junior high school mathematics
1. Given M & sup2; + M-1 = 0, then the value of the algebraic formula M & sup3; + 2m & sup2; + 2007 is__________
2. Given that a, B, C and D are all nonnegative integers, and AC + BD + AD + BC = 2003, find the value of a + B + C + D

First question. ∵ M & sup2; + M-1 = 0
∴m²+m=1-----------①
m³+2m²+2007
=m(m²+m)+m²+2007
Substituting (1) into (2)
m+m²+2007
=1+2007
=2008
Question 2. 2Ac + 2bd + 2ad + 2BC = 4006
a²+c²+b²+d²+2ac+2bd-a²-c²-b²-d²+2ad+2bc=4006
(a+c)²+(b+d)²-(a-d)²-(b-c)²=4006
(a+c-a+d)(a+c+a-d）+(b+d-b+c)(b+d+b-c)=4006
(c+d)(2a+c-d)+(c+d)(2b-c+d)=4006
(c+d)(2a+2b)=4006
(a+b)(c+d)=2003
∵ a, B, C and D are all non negative integers,
2003 is prime, 2003 = 1 * 2003
∴a+b=1,c+d=2003
Or a + B = 2003, C + D = 1
∴a+b+c+d=2004

How to do the seventh question of 16.1 in the second volume of junior high school mathematics?

If the equation | x minus 8 | = a has two real number solutions on [7,9], then the value range of real number a is? 1

|x-8|=a
Then X-8 = a or X-8 = - A
X1 = 8 + A or x2 = 8-A
Because two are in [7,9]
So 7

2 / 7 to 0.5 is the simplest integer ratio. What is the ratio?

2 / 7 to 0.5 is the simplest integer ratio, which is 4:7
2/7:0.5
=2/7:1/2
=2/7*14:1/2*14
=4:7

Choose any 51 numbers from the 100 numbers to 100, and prove that there must be 8 numbers in the 51 numbers, and their maximum value is 0

The title is not clear

Given the function y = LG (AX2 + 2aX + 1): (1) if the domain of definition of the function is r, find the value range of a; (2) if the domain of definition of the function is r, find the value range of A

(1) When a ≠ 0, there should be a ＞ 0 and △ = 4a2-4a ＜ 0, and the solution is a ＜ 1. Therefore, the value range of a is [0,1). (2) if the value range of the function is r, then AX2 + 2aX + 1 can take all positive integers, a ＞ 0 and △ = 4a2-4a ≥ 0. The solution is a ≥ 1, so the value range of a is [1, + ∞)

How many square meters is 20 mu

1 mu ≈ 666.7 square meters
20 mu ≈ 13334 square meters

Calculate the square of [1] y + 2 / y-6y + 9 divided by the square of [3-y] [2] x by [- Y / 1]

[1] The square of Y + 2 / y-6y + 9 divided by [3-y]
=（3-y)²/(y+2)×/(3-y)
=(3-y)/(y+2)
[2] Cubic parts of X, square y of x times [- 1 / y]
=x²y/x³×(-1/y)
=-1/x

Why cos (XY) = - sin (XY) (y + XY ') is not cos (XY)=-
Derivation of implicit functions
cos（xy）=-sin（xy）(y+xy')
Why not cos (XY) = - sin (XY) (y + XY ') y'
Isn't y a function of X? Why don't we take derivatives?

It's time to get a guide
First, the whole is derived from cos, then from XY. According to the derivation rule of multiplication, y + XY '