In 1-100, what are all the natural numbers with only three divisors

In 1-100, what are all the natural numbers with only three divisors

The number of divisors is odd, indicating that the number is a square number
There are only three divisors to show that the number is the square of a prime number
So these numbers are: 2 & # 178; = 4 3 & # 178; = 9 5 & # 178; = 25 7 & # 178; = 49
4 9 25 49

Some people solve the equation as follows: 2 (2X-4) - 12 = 10 (X-5) solution: 4x-8-12 = 10 (X-5), 4x-20 = 10 (X-5)
4 (X-5) = 10 (X-5). Divide both sides by (X-5) to get 4 = 10

Because only when X-5 is not equal to 0, it can be used as divisor

A simple method is used to calculate 12 * (1,2-1,3-1,4) (11,12-5,7) * 7,11,10 and 49,50 * 50 (2,7 + 3,8) * 5.6

If {an} is known to be an increasing sequence and an = N2 + λ n is constant for any n ∈ n *, then the value range of real number λ is ()
A. （-72，+∞）B. （0，+∞）C. [-2，+∞）D. （-3，+∞）

∵ {an} is an increasing sequence, ∵ an + 1 ＞ an, ∵ an = N2 + λ n is constant into immediate (n + 1) 2 + λ (n + 1) ＞ N2 + λ n, ∵ λ ＞ - 2N-1 holds for n ∈ n * constant. When n = 1, the maximum value of - 2N-1 is - 3, ∵ λ ＞ - 3, so D is selected

If the number a is divided by 5 to make 3, and the number B is divided by 5 to make 2, then what is the sum of the two numbers a and B divided by 5? What is the difference between the two numbers a and B divided by 5
What is the difference divided by 5? What is the product of a and B divided by 5?

The sum of a and B is not more than 5
What is the difference divided by 5
Yu 1

3:1-20:9 + 30:4-40:13 + 50:17-72:17

Original form
=3+1/4-9/20+4/30-13/40+17/50-17/72
=3+5/20-9/20+4/30-13/40+17/50-17/72
=3-4/20+4/30-13/40+17/50-17/72
=3-1/5+4/30-13/40+17/50-17/72
=3-6/30+4/30-13/40+17/50-17/72
=3-2/30-13/40+17/50-17/72
=3-1/15-13/40+17/50-17/72
=(2700-60-22.5*13+18*17-17*12.5)/900
=2441/900

Do conics have parametric equations?

Yes
For example: 1. X ^ 2 / A ^ 2 + y ^ 2 / b ^ 2 = 1
Let x = a * Sint, y = b * cost (where a and B are known)
2．x^2/a^2-y^2/b^2=1
Let x = a * sect, y = b * tant (where a and B are known)
Why don't you say no?

If the positive integer solutions of the inequality 2x + K less than or equal to 4-x are 1, 2, 3, then the value range of K is__________

2x+k≤4-x
3x≤4-k
x≤(4-k)/3
Because the positive integer solution of X is 123, 3 ≤ (4-K) / 3 ＜ 4
-8＜k≤-5

Simple calculation of 201.2 * 20.01-201.1 * 19.99

201.2 × 20.01-201.1 × 19.99
= 201.2 × (20 + 0.01) - 201.1 × (20-0.01)
= 4024 + 2.012-4022 + 2.011
＝2＋4.023
＝6.023

The sum of the first n terms of the arithmetic sequence an is Sn, LIM (Sn / N ^ 2) = - A1 / 9 ＜ 0. When finding the value of N, Sn is the largest

Sn=na1+n(n-1)d/2
So LIM (Sn / N ^ 2) = D / 2, that is, D / 2 = - A1 / 9
d=-2a1/9
If - A1 / 9 < 0, then A1 > 0,
An is a decreasing sequence, where an0
So, n = 5 is the largest SN