Use the previous item to show that if ū = (u1, u2) and ✓ = (v1, v2) are vectors in r2 that are not parallel to each other, then any vector (x, y) = r2 can be written as a linear combination of ū and v. in other words, you have to show that for any (x, y) = r2, we can solve the vector equation (x, y) = rũ + sv for r and s. you will have to do a case-by-case analysis. we suggest the cases: (1) neither ui nor uz is zero, and (2) either uż or u2 is zero (explain why they cannot both be zero).