Linear, quadratic, and cubic functions are members of the family of polynomial functions. A polynomial function of degree n is given by ʒ(x) = anxn + anāˆ’1xnāˆ’1 +…+ a1x + a0, where n is a whole number and an, anāˆ’1, …, a1, a0 are real numbers with an ≠ 0.

Consider the key components of this definition to clarify their meanings.

  • Polynomial function of degree n means that the degree of a polynomial is shown in the definition by n. The degree is the highest exponent of any term in the polynomial.

  • Where n is a whole number means that the highest exponent, n, of a polynomial function must be a whole number. It cannot be a fraction, decimal, or negative value. This means that all other exponents in the function must be whole numbers.

  • an, anāˆ’1, …, a1, a0 are real numbers means that, in the function, every coefficient and the constant term, a0, must be real numbers.

  • an ≠ 0 means the leading coefficient, an, cannot be 0. If the leading coefficient is 0, then the leading term is 0, which changes the degree of the polynomial.

Complete the questions on page 287 (1a, 1b, 1c, and 1d) for practice in identifying key features of a polynomial function.

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degree
leading coefficient
constant term