9 Math from scratch
$$ \textbf{X}_2 = \begin{pmatrix} 1&0&0\\1&0&0\\1&0&0\\1&0&0\\1&0&0\\1&0&0\\1&0&0\\1&0&0\\1&0&0\\1&0&0\\1&1&0\\1&1&0\\1&1&0\\1&1&0\\1&1&0\\1&0&1\\1&0&1\\1&0&1\\1&0&1\\1&0&1 \end{pmatrix}. $$
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