Multivariable Polynomials Exercises

Is the following expression a multivariable polynomial? If not, explain why:

x + xy – y

Is the following expression a multivariable polynomial? If not, explain why:

Is the following expression a multivariable polynomial? If not, explain why:

πx² + 3.4xy⁴ + x²y⁵ – 11

Is the following expression a multivariable polynomial? If not, explain why:

x + y + 9^(-1)

Is the following expression a multivariable polynomial? If not, explain why:

5xy – y⁷ + x ^{- 4}y⁴