Talk:Whitehead's lemma

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

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