Final answer:
The expression that matches the description is option (d) 7x^5 + 2x^2 + 6.
Step-by-step explanation:
The expression that matches the description of a 5th degree polynomial with a leading coefficient of 77 and a constant term of 66 is option (d) 7x5 + 2x2 + 6.
To determine if an expression is a polynomial, we check if each term has whole number exponents and no radicals or variables in the denominator. Option (d) satisfies this requirement.
The leading coefficient is the coefficient of the term with the highest degree. In this case, the degree is 5, and the leading coefficient is 7.
The constant term is the term with no variable attached, in this case, 6 is the constant term.
Therefore, option (d) is the correct expression.