i need to prove that for A square matrix: rank AA^t=rank A.(adsbygoogle = window.adsbygoogle || []).push({});

well rank AA^t<=rank A, but how do i show that rankAA^t>=rankA, i mean i need to show if x is a solution of AA^tx=0 then x is a solution of Ax=0 or of A^tx=0, but how?

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# Another question on ranks (linear algebra).

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