We have two rules to determine a monomial:
1. a monomial is a number, variable or product of both.
2. they cannot be divided by a variable
checking for each option:
A. 16 (a number) , yes its a monomial.
B. 2x⁻¹
we can simplify it as 2/x
variable in denominator, so its not a monomial.
C. -x⁹ (variable), yes a monomial.
D. 3x^2 (product of number and variable) , yes its a monomial.
E. √x (variable) , yes its a monomial.
F. x² -2 , (two terms) , so not a monomial