Your grade is based on correctness, completeness, and clarity on each exercise. You may use a calculator, but no notes, books, or other students. 8x2 x3 11x4 = 7. a. ) (5 pts. ) Write the system as a vector equation. b. ) (5 pts. ) Write the system as a matrix equation. c. ) (5 pts. ) Given matrices a = plete the following. State which elementary row operation transforms a into b. b. ) (7 pts. ) By hand, perform the row operations that transform b into reduced echelon form. (continue onto the back of this page if you need more space. ) c. ) (5 pts. ) Construct a 4 4 matrix, not in echelon form, whose columns span r4. Explain how you know the columns span r4. b. ) (5 pts. ) Suppose a system of linear equations has a 2 4 augmented matrix whose fourth column is a pivot column. What is a quick (meaning: no math needed) way to tell that the vectors.