Consider the following matrix, which depends on the parameter y R: -2 1 3 A = 6 3 y -8 2 6 (a) Determine the number of linearly independent columns of the matrix A. (b) If the null space nul(A) is not the zero vector space, find a basis for nul(A). (c) Determine whether or not the matrix A gives rise to an isomorphism of vector spaces. Justify your answer. Your answers to any of the above questions may depend on the value of y E R