Which of the following equations represents a linear regression model?

Which of the following equations represents a linear regression model?

Select one:

a. Y = X2*a

b. Y = 3 - 45X

c. Y = (10-X)3/12

d. Y = 100 + 50X2

Which of the following correlation coefficient values represents the case that when X increases, Y tends to increase, and when X decreases, Y tends to decrease.

Select one:

a. r = -1.0

b. r = -0.12

c. r = 0.0

d. r = 0.99