If A = diag (2, -5, 9), B = diag (1, 1, -4) and C = diag (-6, 3, 4), find
i. A – 2B
ii. B + C – 2A
iii. 2A + 3B – 5C
i. A-2B = diag
-2diag
= diag
-diag
= diag
= diag
Hence, A-2B=diag
ii. B+C-2A
=diag 
+diag
-2diag
=diag
+diag
-diag
=diag
=diag
Hence, B+C-2A=diag
iii. 2A+3B-5C
=2diag
+3diag
-5diag
=diag
+diag
-diag
=diag
=diag
Hence, 2A+3B-5C=diag
5