(1 point) which of the following statements are true? the equation ax = b is consistent if the augmented matrix [ a b ] has a pivot position in every row. b. the equation ax = b is referred to as a vector equation. c. a vector b is a linear combination of the columns of a matrix a if and only if the equation ax = b has at least one solution. d. if the equation ax = b is inconsistent, then b is not in the set spanned by the columns of a. e. if a is an m x n matrix and if the equation ax = b is inconsistent for some b in r™, then a cannot have a pivot position in every row. the solution set of a linear system whose augmented matrix is [ aj a2 a3 b ] is the same as the solution set of ax = b, if a =[ aj az az ].