Which phrase describes a nonlinear function?

•a) the area of a circle as a function of the radius.

•b) the perimeter of a square as a function of the side length.

•c) the cost of gasoline as a function of the number of gallons purchased.

•d) the distance traveled by a car moving at the constant speed as a function of time.

17. a researcher measures three variables, x, y, and z for each individual in a sample of n = 20. the pearson correlations for this sample are rxy = 0.6, rxz = 0.4, and ryz = 0.7. a. find the partial correlation between x and y, holding z constant. b. find the partial correlation between x and z, holding y constant. (hint: simply switch the labels for the variables y and z to correspond with the labels in the equation.) gravetter, frederick j. statistics for the behavioral sciences (p. 526). cengage learning. kindle edition.