Solution
= Solution
The proposed vectors are nonnegative, and direct multiplication gives
$$
\boxed{Ax=\binom11,\qquad A^\mathsf Ty=\begin{pmatrix}1\\5/4\\1\end{pmatrix}.}
$$
Thus $Ax\le\mathbf1$ and $A^\mathsf Ty\ge\mathbf1$, proving primal and <dual feasibility>.