Final answer:
The expression (1/6)x⁴ + (1/8)x is a polynomial because it consists of terms with variables raised to non-negative integer exponents and has constant coefficients.
Step-by-step explanation:
To determine whether the expression (1/6)x⁴ + (1/8)x is a polynomial, we need to look at its characteristics. A polynomial is a mathematical expression that consists of variables and coefficients, involving only the operations of addition, subtraction, multiplication, and non-negative integer exponents of variables. Looking at the given expression, (1/6)x⁴ represents the term with the variable x raised to the fourth power, and (1/8)x is the term with the variable x raised to the first power. Since both terms adhere to the definition of a polynomial, with coefficients (1/6) and (1/8) being constants and the variable x having non-negative integer exponents, we can conclude that the expression is indeed a polynomial.