(a) R2 is a vector space of dimension 2 and R4 is of 4.
two vector spaces are isomorphic if their dimensions are equal.
so, R2 , R4 are not isomorphic.
(b) p5 means the set of all polynomials of degree 5 .
so, its dimension is 6.
it cannot be isomorphic a vector space of dimension 5 which is odf R
5
(c) by assigning


we can show the isomorphism between P5 and M2x3.
( e) is an isomorphism between the space of matrices with dimension 2k and the set of complex numbers of dimension k.