(a) (b) (c) 9 80]~19 7 76 [9+76 7 8 9 3 2 1 6 1 2 3 3 4 5 2 5 1 2 8 10+ 8b 4 5 3 2 7 8 9 k 2k 3k 3 4 2 5 this elementary row operation is known as [Select] 6 1 this elementary row operation is known as [Select] 5 this elementary row operation is known as 1 [Select] V and and [Select] [Select] and [Select]