Is half x + y a monomial?

Is half x + y a monomial?

X + y is not a monomial, it is a polynomial
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Are 5 s and 4 x + y and X-Y of X + y monomials

X + y is monomial
5 of S and X-Y of X + y are not

Is 2 / x + y a monomial
2 is the denominator, x + y is the numerator, and X + y has no bracket, please give the reason

The requirements for a non monomial monomial are as follows:
Monomial:
1. An algebraic expression in the form of the product of any letter and number
2. A letter or number is also called a monomial
3. There is no letter in the denominator
a. - 5,1 x, 2 XY, X / 2 are all monomials, but 0.5 m + N, 2 / X are not
The number of times of a monomial is the sum of the exponents of all the letter factors in a monomial
This term was translated into Chinese by mathematician Li Shanlan in Qing Dynasty
A monomial is the product of a letter and a number
Number of monomials: the sum of the exponents of all letters in a monomial is called the number of times of the monomial
The coefficient of one-way formula: the numerical factor in the monomial formula. For example, the coefficient of 2XY is 2; the coefficient of -- 5zy is -- 5
Notice the third: x + Y / 2 can be reduced to 1 / 2x + 1 / 2Y, so it's not a monomial

1, - 1,3, - 2,9, - 4, () fill in the blanks according to the rule

27-8

Square of 99 + square of 198 + 1
Calculate with multiplication formula````
For example: square difference, perfect square

=(100-1)^2+198+1
=100^2-200+1+198+1
=100^2=10000

The square of 99 + 198 + 1

Square of 99 + 198 + 1
=(99+1)^2
=100^2
=10000

100 divided by (square of 99 + 198 + 1)

100 divided by (the square of 99 + 198 + 1) = 100 / (99 + 1) = 100 / 100 = 1 / 100 = 0.01

Square of 1-99
Because of the area of the circle
I'd like a table with 1 squared, 2 squared, 3 squared, etc
Example: 2 times 2 = 4, 3 times 3 = 9, 4 times 4 = 16
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3.3-5+7-9+11-13… +1995-1997 + 1999 (simple calculation)

1001.3
From 2n + 1, there are 999 numbers
3.3=0.3+3
Expansion is 0.3 + 3-5 + 7-9... + 1999
Sorting: 0.3 + (3-5) + (7-9) +... + (1995-1997) + 1999
In brackets, they are all equal to - 2, that is, 998 △ 2 × (- 2) = - 998
0.3-998+1999=1001.3

1-3+5-7+9-11+13-15+...-1995+1997-1999+2000

1-3+5-7+9-11+13-15+...-1995+1997-1999+2000
=(1-3)+(5-7)+(9-11)+(13-15)+...-1995+(1997-1999)+2000
=500*(-2) + 2000=1000