(i) A−1=[1174120−1201311613]\boxed{A^{-1}=\begin{bmatrix}1&\frac{17}{4}&\frac{1}{2}\\0&-\frac{1}{2}&0\\\frac{1}{3}&\frac{11}{6}&\frac{1}{3}\end{bmatrix}}A−1=1031417−2161121031