Determinants & inverses of large matrices

Inverse of a 3x3 matrix

Problem

E=[210200201]\textbf E = \left[\begin{array}{rrr}2 & 1 & 0 \\ 2 & 0 & 0 \\ 2 & 0 & 1\end{array}\right]
What is E, start superscript, minus, 1, end superscript?
Do 4 problems
Do 4 problems