A formula that represents the product of numbers or letters is called a monomial. The numerical factor in the monomial is called the coefficient of the monomial. In a monomial, the sum of the exponents of all the letters is called the degree of the monomial. The zeroth power of any nonzero number is equal to 1.

note:

1, the formula with letters in the denominator is not a monomial, because the monomial belongs to an algebraic expression, and the formula with unknown denominator is a fraction. For example, 1/x is not a monomial.

2. A single number or letter is also a monomial. For example, 1 and x^2y are also monomials.

3. When the monomial indicates that a number is multiplied by a letter, the number is usually written in front.

6. If a monomial only contains letter factors, then its coefficient is 1 if it is positive, and-1 if it is negative.

5. If the monomial only contains numerical factors, then its degree is 0.