Det M of 2x2 matrix can be any value from -infty to +infty E) B1+B2 will have a21 as 0 hence belong to the group and Identity element is 0 matrix Inverse of B = -B Hence B is a subgroup 2) Solution Det M of 2x2 matrix can be any value from -infty to +infty E) B1+B2 will have a21 as 0 hence belong to the group and Identity element is 0 matrix Inverse of B = -B Hence B is a subgroup 2).