(1 point) a is an n×n matrix. check the true statements below: a. a number c is an eigenvalue of a if and only if the equation (a−ci)x=0 has a nontrivial solution x. b. finding an eigenvector of a might be difficult, but checking whether a given vector is in fact an eigenvector is easy. c. a matrix a is not invertible if and only if 0 is an eigenvalue of a. d. to find the eigenvalues of a, reduce a to echelon form. e. if ax=λx for some vector x, then λ is an eigenvalue of a.

Isuck at math ; ^; m a student solved this problem and said the answer is 3 feet. chase had a roll of ribbon that contained 7 7/8  feet of ribbon. he cut off one piece that was 3 5/8  feet long and another piece that was 1 1/4  feet from the roll. how much ribbon was left on the roll? is the student's answer reasonable? yes, the answer is reasonable. no, the answer is not reasonable. it should be about 2 feet. no, the answer is not reasonable. it should be about 13 feet. no, the answer is not reasonable. it should be about 4 feet.