Prerequisites - P.3 - Polynomials and Special Products - Exercises - Page 31: 15

Yes

It is a polynomial since the coefficients of each term are real numbers and also the power of each variable in each term is a non-negative integer. Look at the definition of a polynomial given on page 28. A polynomial is said to be in standard form if each of the terms is written such that the degrees of each term are in descending order. $-y^4+y^3+y^2$