Is 3 / x-x a monomial 3 / x-x is a polynomial on the surface, but the result is a monomial. Is it a monomial or a polynomial

Is 3 / x-x a monomial 3 / x-x is a polynomial on the surface, but the result is a monomial. Is it a monomial or a polynomial

It's a polynomial
It can be decomposed into 3 / X-1

Is x + 1 a monomial
Is one part of x a monomial? Is π (the square of R) a monomial? Is the square of two-thirds of a monomial? Is B a monomial

No
It's a polynomial with two terms
Definition of monomial: a single number, a letter or the product of a number and a letter is called a monomial

Is 1 / X-1 a monomial
one
--
x-1

No, it's a fraction

What is the value of 1 + 3 + 5 + 7 + 9 +,,, + 2n-3 + 2N-1?

Because an - an-1 = (2n-1) - (2n-3) = 2
This is the arithmetic progression:
First term: A1 = 1, last term: an = 2N-1, number of terms: n
1 + 3 + 5 + 7 + 9 +,,, + 2n-3 + 2N-1: n / 2 (a1 + an)
= n/2 (1+2n-1)
= n^2

1+3+5+7+9+…… +What is the value of 2n-3

This is the sum of the number of items of an arithmetic sequence with the first term of 1, the tolerance of 2, and the number of items of n-1
(n-1) (1 + 2n-3) / 2 = (n-1) ^ 2 = n ^ 2-2n + 1, where n ≥ 2

394 + 395 + 396 + 397 + 398 + 399 + 400 by simple method

394+395+396+397+398+399+400
=400-6+400-5+400-4+400-3+400-2+400-1+400
=400*7-（1+2+3+4+5+6）
=2800-21
=2779

What is 398 + 397 + 401 + 395 + 412 + 407 + 401 + 395 + 408 + 399 + 407 + 400 + 403?

398+397+401+395+412+407+401+395+408+399+407+400+403=400-2+400-3+400+1+400-5+400+12+400+7+400+1+400-5+400+8+400-1+400+7+400+400+3=400*13+(-2-3+1-5+12+7+1-5+8-1+7+3)=5200+23=5223

What is the rule of 395 + 396 + 397 + 398 + 399 + 400 + 401 + 402 + 403 + 404 + 405

400 times 11
Or the first plus the penultimate, the second plus the penultimate, the second in turn

How to calculate 399 + 398 + 397 + 396

Original formula = 400 + 400 + 400-1-2-3-4 = 1600-10 = 1590
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Calculation 0.1 + 0.3 + 0.5 + 0.7 + 0.9 + 0.11 + 0.16 +... + 0.97 + 0.99=

Count the first five and the last 45
（0.1+0.9）*5/2+(0.11+0.99)*45/2=27.25