4. Practice working with If. Then statements: (a) [5 points| Prove the following statement is true: For all vectors x, u, v, w B: If x span{2u + w,u v}, then x span{u, v, w}. (b) |5 points| Provide a counterexample in R? that disproves the following statement: For all vectors x,u, v, w E": If x span{u, v, w}, then x span{2u + w.u v}