which of the following gives an example of a function that is not linear?

A. 9x+3y-18=0

B. y=x^2 - 3x + 2.25

C. 2x + 3y = 16

D. y =1/6x+2/3

The function that is not linear among the given examples is:

B. y = x^2 - 3x + 2.25

This equation represents a quadratic function due to the presence of the x^2 term. Quadratic functions are not linear because they include a term with the independent variable raised to the second power. Linear functions have a degree of one and are characterized by a constant rate of change, indicated by a straight line when graphed. Quadratic functions, on the other hand, have a variable rate of change and form a parabolic curve when graphed.