Answer
$D=A^{-1}$
Work Step by Step
Let $A$ be invertible and $AD=I$
$AD=I$
$A^{-1}(AD)=A^{-1}I$
$(A^{-1}A)D=A^{-1}$
$ID=A^{-1}$
$D=A^{-1}$
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.