It is proved that the arithmetic sequence {an} with odd 2n terms has s odd-s even = an, s odd / s even = n / n-1

It is proved that the arithmetic sequence {an} with odd 2n terms has s odd-s even = an, s odd / s even = n / n-1

This question should be two questions: in the arithmetic sequence,
(1) If the number of items is even 2n, then s even-s odd = Nd (D is the tolerance);
(2) If the number of terms is odd 2N-1, then s odd / s even = n / (n-1)
It is proved that: (1) s odd = a1 + a3 + +A (2n-1) of n terms (2n-1 is subscript)
S even = A2 + A4 + +A2N of n (2n is subscript)
S even-s odd = (a2-a1) + (a4-a3) + +[a2n- a(2n-1)]=nd
(2) S odd = a1 + a3 + +A (2n-1) of n terms (2n-1 is subscript)
=[a1+a(2n-1)]•n/2
S even = A2 + A4 + +A (2n-2) of n-1 terms (2n-2 is subscript)
=[a2+a(2n-2)]•(n-1)/2
∵a1+a(2n-1)=a2+a(2n-2)
S odd / s even = n / (n-1)

Xiao Li, Xiao Liu and Xiao Wang, one of them teaches Chinese, one math and one English
It is known that Xiao Li and his Chinese teacher are different ages. Xiao Liu and his Chinese teacher live in the same community. Xiao Liu and his math teacher often play chess. What subjects do the three teachers teach

Xiao Wang -- Chinese teacher
Xiao Liu, an English teacher
Xiao Li -- Mathematics Teacher

Miss Liu, this is my mother
Mr.Liu , __ __ my mom

Miss/ Mr Liu, this is my mother.
I wish you progress in your studies and make progress! (*^__ ^*)
If you don't understand, please take it in time. Thank you!

Liu said, "this semester, I'll teach you English."

This term I will teach you English.

Hello, Miss Liu. I'm XXX from class 52?

Hello ,Mr Liu, I am XXX from Class two , Grade five .
Hello, can be specific to: Good morning / after noon / evening and so on

Solving two problems of Fractional Inequality: x-3 / (2x + 1) ≤ 0 (- 2x + 3) / (x-1) - 2 > 0
（x-3）/（2x+1）≤0
（-2x+3）/（x-1）-2>0
The above two questions=

Hello
The answer to the first question: equivalent to: x-3 = 0, 2x + 1 = 0, the solution is x = - 1 / 2, 3
So it is [- 1 / 2,3]
The second question: first, divide in a similar question: [1,5 / 4]
thank you
Hope to help you
I wish you a better study

(1) When (), the fraction x + 1 is meaningless. (2) when (), the fraction 2x + 1 is meaningful. (3) when (), the value of fraction 2x + 1 is zero

1.-1
2. Not equal to - 1 / 2
3.x=-1
The denominator is zero, the numerator is zero and the denominator is not zero

In the math self-study class, the teacher assigned a math homework problem: two polynomials are a and B, where a = 2A ^ - 3a-7, Xiaowei solved "a + B" again
The first is the best, then add 10 points
My question is not complete. In my self-study class, the teacher assigned a math assignment: two polynomials are a and B, where a = 2A ^ - 3a-7. Xiaowei takes "A-B" as "A-B" when he seeks "a + B", and the answer is - A's quadratic power - 8A + 3, so what's the exact result of "a + B"?

A-B=-a²-8a+3
∴B=A-a²-8a+3
=2a²-3a-7+a²+8a-3
=a²+5a-10
∴A+B=2a²-3a-7+a²+5a-10
=3a²+2a-17

If polynomial a subtracts - 3x to get polynomial X & # 178; - 3x + 6, then polynomial A is []
A.x²-6x+6 B.x²+3x+6 C.x²-6x D.x²+6

A=(x^2 -3x+6)+(-3x)
=x^2 -6x+6
The answer is a

Mr. Wang asked a question on the blackboard: is the square of fraction x-9:2x + 6 and x-3:2 the same fraction? Why? Xiaoming and Xiaoqing answered this question. Xiaoming said: because the square of fraction x-9:2x + 6 = (x + 3) (x-3) 2 (x + 3) = x-3:2, so it is the same fraction. Xiaoqing said: because the square of fraction x-3 = x + 3) (x-3) 2 (x + 3) = x-9:2x + 6, So it's the same fraction. Do you agree with them

In the first formula, X can't go to - 3, but the second one can