Let {e1,e2} be a basis in R3 . Then
Wn={α(e1+ne2),α∈R},n∈N
are all different proper vector subspaces. Indeed, suppose Wn=Wm .
Then e1+ne2=α(e1+me2) for some α.
Then (α−1)e1+(mα−n)e2=0
From which α=1,α=n/m,i.e. n=m.
This proves that Wn are all different. And there are infinitely many of them.
Conclusion: R3 has infinitely many nonzero, proper vector subspaces - true.
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