Problem numbers refer to the poole textbook (4th edition) 1. let a, b, c, be three points in the plane. let o denote the origin. (a) suppose a (1, 1) and b (3,2). sketch ab, and find r, y er such that ab (b) express ab as a linear combination of oa and ob. provide a sketch to support your answer. (e) express -2bč as a linear combination of ab and ac. provide a sketch to support your answer. (d) if a (1, 1), b (3, 2), c (0,-1), find r, y er such that 2ab-4ca