4. (a) LetU={A∈M2×2(R)|Tr(A)=0},and let
4 .( a ) Let U = [ A E M 2 x 2 (RX ) | Ir ( A ) = Of, and let$ = { ( 6 – 1 ) . ( 2 ) ? ) . ( 2 21 ) . ( 3 – 2 ) . (` 2] ) }a subset of U. Find a basis for Us contained in S .( b ) Let IT be the subspace of P spanned byI = fad + 2 } + 2 + 1, 28 + 2 20 2 + 320 – 1.2 20% + 3 20 2 + Ax . as + ac , – 28 + 2 20 2 + 20 – 1).Find a basis for IT contained in I .