So I had a quiz on Wednesday and got the problem wrong but don't know why. The question is: Use elementary row operations to reduce the matrix A= 3 1 -1 2 3 1 -4 0 2 to upper-triangular form. Each of these elementary row operations should have the form Ri :=Ri-likRk where lil is an appropriate multiplier. Show the values of each of the ilk's and the order in which each of the elementary row operations is applied. (For this exercise, do not interchange any rows.) Hint: When you are done, the product of the three pivots should be -2. I had l21= 2/3 and did R2:= R3=2/3R1 and and then did l31=-4/3 R3:=-R3-(-4/3)R1 My matrix at the end was 3 1 -1 0 7/3 5/3 0 0 2/3 Which is upper triangular form, but incorrect. What did I do wrong?