Question:
\([\,{-}1\,]\,[\,1\ \ {-}1\,]=\ \ ?\)
\([\,{-}1\,]\,[\,1\ \ {-}1\,]=\ \ ?\)
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Scalar $\times$ matrix $=$ scale every entry by the scalar.
Updated On: Oct 17, 2025
- \([\,0\,]\)
- \([\,{-}1\ \ 1\,]\)
\(\begin{bmatrix}-1 \\ 1\end{bmatrix}\)
- \([\,2\ \ {-}2\,]\)
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The Correct Option is B
Solution and Explanation
Think of \([\,{-}1\,]\) as a plain number \(-1\). When a scalar multiplies a matrix (or row), it multiplies each entry.
So,
\[
[\,{-}1\,]\,[\,1\ \ {-}1\,]
=[\,{-}1\times 1\ \ {-}1\times(-1)\,]
=[\,{-}1\ \ 1\,].
\]
That's all—entrywise scaling.
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