Identify the following expression as monomial, binomial, trinomial and polynomial.

$x+2$

Identify the following expression as monomial, binomial, trinomial and polynomial.

$y^2+2xy+x^2$

Identify the following expression as monomial, binomial, trinomial and polynomial.

$10$

Identify the following expression as monomial, binomial, trinomial and polynomial.

$a^2+b^2$

Identify the following expression as monomial, binomial, trinomial and polynomial.

$7x^3+5x^2+2x+7$

Identify the following expression as monomial, binomial, trinomial and polynomial.

$2a$

Identify the following expression as monomial, binomial, trinomial and polynomial.

$5xy + 7yz + 9zx + 9x$