Compute the following:
`[(a,b),(-b,a)]+[(a,b),(b,a)]`
(ii) `[(a^(2)+b^(2),b^(2)+c^(2)),(a^(2)+c^(2),a^(2)+b^(2))]+[(2ab,2bc),(-2ac,-2ab)]`
(iii) `[(-1,4,-6),(8,5,16),(2,8,5)]+[(12,7,6),(8,0,5),(3,2,4)]`
(iv) `[(cos^(2)x, sin^(2)x),(sin^(2)x, cos^(2)x)]+[(sin^(2)x, cos^(2)x),(cos^(2)x, sin^(2)x)]`

Answer

`(i) [(2a,2b),(0,2a)] (ii) [((a+b)^(2),(b+c)^(2)),((a-c)^(2),(a-b)^(2))]`
`(iii)[(11,11,0),(16,5,21),(5,10,9)] (iv) [(1,1),(1,1)]`