For integer x only, is x considered a polynomial?

In summary, for integer x only, x! is not considered a polynomial because it does not satisfy the definition of a polynomial function. A polynomial function has a specific form and x! does not fit that form, despite being equal to a constant value for a specific integer x. Additionally, x! does not satisfy the definition of a polynomial because it is not a function, but rather a value of a function.
  • #1
tgt
522
2
For integer x only, is x! considered a polynomial?
 
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  • #2


no 4char
 
  • #3


well,
x! = x * (x - 1) * (x - 2) * ... * 2 * 1

And for any integer x! = n where n is some integer.

So, is an integer a polynomial?
 
  • #4


Diffy said:
well,
x! = x * (x - 1) * (x - 2) * ... * 2 * 1

And for any integer x! = n where n is some integer.

So, is an integer a polynomial?
That's a strange response! For any integer, x, x2= n where n is some integer.
Is an integer a polynomial? No, of course not. But that has nothing at all to do with whether or not x2 is a polynomial, which it is.

x!, for x a positive integer is not a polynomial but for a very different reason: because it does not satisfy the definition of "polynomial".
 
  • #5


From Wikipedia:
A function ƒ of one argument is called a polynomial function if it satisfies

for all arguments x, where n is a nonnegative integer and a0, a1,a2, ..., an are constant coefficients.

I think integer fits this definition since n is allowed to be 0, no?
 
  • #6


Yes, you can think of the constant function, whether or not it is an integer, as a polynomial. But that still has nothing to do with the question. Surely you are not confusing a function with a value of the function?
 
  • #7


I would think that is exactly what I am doing. I apologize tgt if I mislead you.
 

1. Is x considered a polynomial if it is an integer?

Yes, x can be considered a polynomial if it is an integer. A polynomial is an expression that can be written as the sum of terms, each consisting of a variable raised to a non-negative integer power, multiplied by a coefficient. Since x can be written as x^1, which follows the definition of a polynomial, it is considered one.

2. Can x be considered a polynomial if it is not an integer?

No, x cannot be considered a polynomial if it is not an integer. As stated previously, a polynomial requires a variable raised to a non-negative integer power, and if x is not an integer, it cannot satisfy this requirement. However, x can still be a part of a larger polynomial expression if it is combined with other terms.

3. Why is it specified that x is for integers only?

In mathematics, it is important to be specific about the variables used in an equation or expression. By specifying that x is for integers only, it eliminates any confusion or ambiguity about what values x can take on. It also helps in simplifying the expression and making it easier to solve.

4. What happens if x is not an integer but is still used in a polynomial expression?

If x is not an integer but is still used in a polynomial expression, then the expression will no longer be considered a polynomial. It may still be a valid mathematical expression, but it will not follow the definition of a polynomial. The resulting expression may be a rational function or a radical expression, depending on the specific values of x.

5. Can x be an integer and still not be considered a polynomial?

Yes, x can be an integer and still not be considered a polynomial. This can happen if x is a constant in an expression, such as in the expression 3x + 5, where x is an integer but not the variable in the polynomial. In this case, x is just a coefficient, and the polynomial is 3x, which follows the definition of a polynomial.

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