Let $A$ = $\left[\begin{array}{cc} -6 &-7\cr 14 &15 \end{array}\right]$
Find a matrix $S$, a diagonal matrix $D$ and $S^{-1}$ such that $A=SDS^{-1}$.

$S =$ $\left[\Rule{0pt}{2.4em}{0pt}\right.$$\left]\Rule{0pt}{2.4em}{0pt}\right.$,  $D =$ $\left[\Rule{0pt}{2.4em}{0pt}\right.$$\left]\Rule{0pt}{2.4em}{0pt}\right.$,  $S^{-1} =$ $\left[\Rule{0pt}{2.4em}{0pt}\right.$$\left]\Rule{0pt}{2.4em}{0pt}\right.$