After three consecutive natural numbers 1, 2, 3 are removed, the average of the remaining numbers is 19 and 8 / 9 If there are exactly two primes in the number, what is the maximum sum of the two primes?

After three consecutive natural numbers 1, 2, 3 are removed, the average of the remaining numbers is 19 and 8 / 9 If there are exactly two primes in the number, what is the maximum sum of the two primes?

First of all, we should know that the average number of several natural numbers is more than 19, so the total number is about 40, then it is 19 and 8 / 9, so after removing three numbers, the total number is a multiple of 9, so it is 36, so the original is from 1 to 39, the total is 20 * 39 = 780, removing three numbers, the total is 19 and 8 / 9, multiplied by 36 = 716, so the three removed

Use multiplication to find the sum of 16 + 17 + 18 + 19 + 20 = () * () = ()
Find the sum of the following expressions by multiplication
16+17+18+19+20=（ ）x（ ）=（ ）

16 + 17 + 18 + 19 + 20 = 18x5 = 90, because the difference between every two numbers is 1, you can calculate (the first number + the second number) multiplied by the number of numbers, and then divided by 2, which part of the high middle arithmetic sequence

What's the integral of LNX
Indefinite integral of LNX
Can you write down the solution process?

The equation x ^ 2-ax + A ^ 2-4 = 0 of X has two positive roots, so we can find the value range of real number a

⊿=a²-4（a²-4）≥0,
The product of two is a & sup2; - 4 > 0,
The sum of the product of two - a ＞ 0
The simultaneous solution is - 4 √ 3 / 3 ≤ a ＜ - 2

What are the factors of 37

1 and 37

On the limit of function of higher numbers,
Why is Lim x-0 x-sinx 1-cosx equal to 0? Sometimes it is said that SiNx cosx is in oscillation? When is it in oscillation

When x → 0, X is equivalent to SiNx
∴lim(x-sinx)=0
x→0
Similarly, when x → 0, limcosx = 1;
∴lim(1-cosx)=lim(1-1)
x→0 x→0
=0
When x →∞, SiNx and cosx oscillate and oscillate between [- 1,1], so when x →∞, SiNx and cosx have no limit

Solving equations y = 2x 2x + y = 4 by image method

2x+y=4①
y=2x ②
Substitute (2) for (1)
2y=4
y=2
Substituting y = 2 into 2
2x=2
x=1
The solution of the original equations is x = 1, y = 2

1, 121, 231, 234, 123, 451, 23456

an=1*10^(n-1)+2*10^(n-2)+.+n*10^0(n>0)

It is proved that limf (x) (x tends to x0) = a is equivalent to any {xn}. When xn tends to XO, f (xn) tends to a

It is proved that limf (x) (x tends to x0) = a deduces that for any {xn}, when xn tends to XO, f (xn) tends to a δ ε
For any δ, because limf (x) (x tends to x0) = a, there exists ε when | x-x0|

Use the program to calculate the following expression: S = 1! + 2! + 3! + 4!

int sum=0,k=1;
for (int i=1;i