If a natural number is divided by 3, that is, the natural number is reduced by 1-3 meters. Right or wrong?

If a natural number is divided by 3, that is, the natural number is reduced by 1-3 meters. Right or wrong?

yes

Judge the relationship between the following two sets: a = {x = 3k, K ∈ n}, B = {x = 6Z, Z ∈ n}
And I want to know what a = {1,2,3,4} means. For example: is a equal to 1234 curly braces? I don't understand many of them

In B, x = 2 * (3Z)
In a, x = 3K
k、z∈N
So x in a can be regarded as all integers
In B, X can be regarded as all even numbers
So B is the proper subset of A
A={1,2,3,4}
A is a set of 1, 2, 3 and 4 elements

It is known that each item of the equal ratio sequence {an} is a positive number, and a1,1 / 2a3,2a2 are equal difference sequence, find (A9 + A10) / (A7 + A8)

The square of x-5x + 1 = 0 find the fourth power of X + the fourth power of X

The square of X is - 5x + 1 = 0. Obviously, X is not equal to 0. Dividing both sides by X at the same time, we get] X-5 + (1 / x) = 0 x + (1 / x) = 5, we get X & # 178; + (1 / x) & # 178; + 2 = 25X & # 178; + (1 / x) & # 178; = 23, we get x ^ 4 + (1 / x) ^ 4 + 2 = 529x ^ 4 + (1 / x) ^ 4 = 527

Solving the non-zero solution of sin (x) = x * (1 / 3) by MATLAB
Do not draw a picture. Thank you very much

>> syms x;f=inline('sin(x)-x*(1/3)')
f =
Inline function:
f(x) = sin(x)-x*(1/3)
>> fplot(f,[-10,10])
>> grid
It can be seen from the image that there are two non-zero solutions between [- 4, - 2] and [2,4], so use the following two commands
>> [xroot,y]=fsolve(f,[2,4],1e-5)
Optimization t erminated:first-order optimality is less than options.TolFun .
xroot =
2.278862660075828 2.278862660076503
y =
1.0e-012 *
0 -0.663136212608606
>> [xroot,y]=fsolve(f,[-4,-2],1e-5)
Optimization t erminated:first-order optimality is less than options.TolFun .
xroot =
-2.278862660076468 -2.278862660075828
y =
1.0e-012 *
0.629607477264926 0
Note that the final result xroot is the final interval (precision is 1e-5), that is, the root of the equation is between [2.278862660075828 2.278862660076503], and Y is the function value obtained by substituting this value into F

Three fives and one one, divide by addition and subtraction, no matter how you calculate, but the result should be equal to 24?
Let's think about it

5*(5-1/5)=24

As shown in the figure, two parallelograms A and B are overlapped. The area of the overlapped part is 14 of a and 16 of B. It is known that the area of a is 12 square centimeters. Then the area of B is more than that of A______ Square centimeter

The area of B is a: (1 △ 16) / (1 △ 14), = 6 △ 4, = 1.5 (Times); the area of B is more than that of a: 12 × (1.5-1), = 12 × 0.5, = 6 (square centimeter); a: the area of B is more than that of a: 6 square centimeter

Given that the vertex of quadratic function image is (- 3,4) and passes through the point (1, - 2), the expression of quadratic function is obtained

Solution
∵ vertex is (- 3,4)
Let the quadratic function be y = a (x + 3) &# 178; + 4
∵ passing point (1. - 2)
∴a(1+3)²+4=-2
∴16a=-6
∴a=-3/8
∴y=-3/8(x+3)²+4

If the algebraic formula (2k-1) x2 + 2 (K + 1) x + 4 is a complete square, then the value of K is

When (2k-1) x ^ 2 + 2 (K + 1) x + 4 = [√ (2k-1) x] ^ 2 + 2 (K + 1) x + 2 ^ 2 is a complete square form, it can only be written in the following form [√ (2k-1) x ± 2] ^ 2 = [√ (2k-1) x] ^ 2 ± 4 √ (2k-1) x + 2 ^ 2 by the equations [√ (2k-1) x] ^ 2 + 2 (K + 1) x + 2 ^ 2 and [√ (2k-1) x] ^ 2 ± 4 √ (2k-1) x + 2 ^ 2

Use a piece of circular paper to cut into the largest square. The known diameter is 6cm. How much is the area of the paper to be cut

3.14×6/2×6/2-6×6/2
=3.14×9-18
=28.26-18
=10.26 square centimeter