Decide whether each map is an isomorphism

[danni7070]

Homework Statement

Decide whether each map is an isomorphism (if it is an isomorphism then
prove it and if it isn’t then state a condition that it fails to satisfy).

Homework Equations

f : M2×2 ---- P^3 given by:

a b
c d --- c + (d + c)x + (b + a)x^2 + ax^3

The Attempt at a Solution

Ok, I know that map is isomorph if it is one-to-one and onto.

I know it is one-to-one but I'm having problems showing that it is onto because I get confused using polynomials!

Can somebody give me a hint?

 

[radou]

What does it mean (for a mapping) to be onto?