The variable selection procedure that identifies the best regression model, given a specified number of independent variables, is a. stepwise regression. b. best-subsets regression. c. backward elimination. d. forward selection.

The vertices of a rectangle are given in the columns of the matrix . if is found to perform a transformation, what are the coordinates of the transformed rectangle? (0, 0), (0, –3), (–3, –3), (–3, 0) (0, 0), (0, 3), (3, 3), (3, 0) (0, 0), (0, 3), (–3, –3), (–3, 0) (0, 0), (0, 3), (–3, 3), (–3, 0)

How to do this , and can some one explain

Write a function for a rotation 90 degrees counter clockwise about the origin, point 0