Question

If $A=\left[\begin{array}{ccc}1&0&1\\0&1&2\\0&0&4\end{array}\right]$ then show that |3A| = 27|A|

Answer 1

Answer:

They are right aligned because you have {array}{lr} change that to {array}{ll} to left align both columns. But generally it is best not to use array for laying out whole equations, it is designed for matrices/arrays. Here I think the amsmath package and its cases environment would be better.

HOPE IT HELPS ✌