Talk:Whitehead's lemma

The formula displayed doesn't seem to be correct. I believe a correct possibility would be:

$$ \begin{bmatrix} u & 0 \\ 0 & u^{-1} \end{bmatrix} = e_{21}(u^{-1}) e_{12}(-u) e_{21}(u^{-1}) e_{21}(-1) e_{12}(1) e_{21}(-1) $$