Write the constant term of the following algebraic expressions:

$7x^2-9$

Write the constant term of the following algebraic expressions:

$x^{2}y-x{y}^2+7xy-3$

Write the constant term of the following algebraic expressions:

$2x^2-x$

Identify the like terms in the following algebraic expression:

${\mathrm{a}}^2+{\mathrm{b}}^2-2{\mathrm{a}}^2+{\mathrm{c}}^2+4\mathrm{a}$

Identify the like terms in the following algebraic expression:

$3x+4xy-2yz+\frac{5}{2}zy$

Identify the like terms in the following algebraic expressions:

$x^{2}y-2x{y}^2+5y^{2}x+x^{2}z$

Write the degree of the polynomials:

$3a^2$

Write the degree of the polynomials:

$\frac{4}{7}-\frac{3}{2}x+x^2-\frac{3}{2}{x}^3$

Write the degree of the polynomials:

$\frac{3}{10}{x}^7-2x+\frac{5}{9}$