Natural numbers can be divided into two categories, namely ()

Natural numbers can be divided into two categories, namely ()

Natural numbers can be divided into two categories: odd and even

What is the natural number divided into?

There are two categories
① According to parity, it can be divided into odd number and even number
② According to the number of factors, it can be divided into prime number, composite number and 1 (neither prime nor composite number)

The number of natural numbers can be divided into (), (), ()

Natural numbers can be divided into three categories: ① 1, ② prime numbers and ③ composite numbers

It is known that the height of a cone is 3cm and the radius of its bottom is 4cm. What is the square area of its axis
Just asked a question... But I found the wrong type
Given that the height of a cone is 3cm and the radius of its bottom is 4cm, how many cm square is the cross-sectional area of its axis?

The section through the axis is a triangle
Bottom edge length = 4 × 2 = 8cm
Height = 3cm
Cross sectional area = 8 × 3 △ 2 = 12cm & # 178;

Simple calculation of 3 / 2 * 4 / 3 * 5 / 4 *... * 51 / 50
It's tonight

The numerator of the first number and the denominator of the second number are approximately divided, so that only the denominator of the first number and the numerator of the last number are left, that is, 3 / 2 * 4 / 3 * 5 / 4 *... * 51 / 50 = 51 / 2

Circle C passes through three different points P (k, 0), q (2, 0) and R (0, 1). It is known that the tangent slope of circle C at point P is 1. Try to find the equation of circle C

Suppose that the equation of circle C is x2 + Y2 + DX + ey + F = 0, then K and 2 are two of x2 + DX + F = 0, ∧ K + 2 = - D, 2K = f, that is, d = - (K + 2), f = 2K, and then circulates over R (0, 1), so 1 + e + F = 0. ∧ e = - 2k-1

If A1 (x-1) 4 + A2 (x-1) 3 + A3 (x-1) 2 + A4 (x-1) + A5 = x4, then the value of A2 + a3 + A4 is______ ．

The original equation can be changed as: A1 (x-1) 4 + A2 (x-1) 3 + A3 (x-1) 2 + A4 (x-1) + A5 = [1 + (x-1)] 4. Let x = 2, a1 + A2 + a3 + A4 + A5 = 24, obtained from the general formula of binomial expansion, A1 = 1, A5 = 1. So A2 + a3 + A4 = 14

Given that positive real numbers x and y satisfy 1 / (2x + y) + 4 / (2x + 3Y) = 1, then the minimum value of X + y is?

1 / (2x + y) + 4 / (2x + 3Y) = 1 can be changed into: 1 / (2 (x + y) - y) + 4 / (2 (x + y) + y) = 1, so that M = 2 (x + y) can be changed into 1 / (M-Y) + 4 / (M + y) = 1. This function can be expressed as a hyperbola m + y + 4 * (M-Y) = m ^ 2 - y ^ 2m ^ 2 - 5 * m = y ^ 2-3 * YM ^ 2-5 * m + 9 / 4 = (Y-3 / 2) ^ 2 > = 0m ^ 2 - 5 * m + 9

1 / 2, 3 / 6, 5 / 12. What's the 100th number

Observation shows that the nth number is (n-1) power of (- 1) * (2n-1) / [n * (n + 1)]
So n = 100 hours is - (200-1) / (100 * 101) = - 199 / 10100

The equations of 5x + 4Y + Z = 0 3x + y-4z = 11 x + y + Z = - 2
A system of equations in which three equations are combined

5x+4y+z=0 3x+y-4z=11 x+y+z= -2
4x+3y=2
7x+5y=3
20x+15y=10, 21x+15y=9
x=-1
y=2
z=-3