Suppose that a is a square matrix with characteristic polynomial (λ − 3)2(λ − 6)3(λ + 1). (a) what are the dimensions of a? (give n such that the dimensions are n × n.) n = 6 correct: your answer is correct. (b) what are the eigenvalues of a? (enter your answers as a comma-separated list.) λ = 3,6,−1 correct: your answer is correct. (c) is a invertible?