Suppose $V$, $W$ are Banach spaces and $f$, $g:V \rightarrow W$ are continuous linear operators and $\operatorname{Im}f$, $\operatorname{Im}g$ are closed subspaces of $W$. Is it true that $\operatorname{Im}(f+g)$ is closed too?
2026-04-11 16:50:51.1775926251
Is image of sum of maps closed?
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