Which of the following is a monomial?

Which of the following is a monomial?
  1. $x + y$
  2. $5xy^{2}$
  3. $x^{2} + 2x + 1$
  4. $2x - 3y$

Solution

A monomial is a single term. Only $5xy^{2}$ has just one term.

Asked in: IMO

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