Last problem:

Suppose that V is a vector space over any field F and that U and W are

subspaces of V.

Let V=C[X], the vector space of all polynomials over complex numbers. Let U=Span{1+(1+i)X^2, (1+2i)+iX+X^4} and W=Span{X+(2-i)X^2+(3+i)X^3, (2+2i)+(1+i)X+3X^2+(3+i)X^3+2iX^4}. Show that the sum U+W is actually a direct sum and conclude that U+W has a basis with four elements.

Thank you so much.