Is the following expression a multivariable polynomial? If not, explain why:
x + xy - y
No. We are not allowed to divide by a variable in a polynomial.
πx2 + 3.4xy4 + x2y5 - 11
x + y + 9(-1)
Yes. In a polynomial, we are allowed to raise constants to negative exponents. It just gets us different constants, which we can live with.
5xy - y7 + x - 4y4
No. We are not allowed to raise variables to negative exponents in polynomials.
Make it rain.