Answer:
B. The function is nonlinear.
Step-by-step explanation:
A linear function graphs as a straight line. It is a polynomial function of degree 1. Any function that is not a linear function is a nonlinear function.
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degree
The function given is a polynomial function of degree 2. (Its highest-degree term is x^2, which has an exponent of 2.)
categorization
Since the degree is not 1, the function is nonlinear.
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Additional comment
A polynomial function will never be "linear at some points and nonlinear at other points." Such a description might apply to a piecewise-defined function.
