i. (4xy – 9z) – (3xy – 16z)
= 4xy – 9z – 3xy + 16z
= (4xy – 3xy) + (16z – 9z)
= xy + 7z
ii. (5x + 4y + 7z) – (x + 2y + 3z)
= 5x + 4y + 7z – x – 2y – 3z
= (5x – x) + (4y – 2y) + (7z – 3z)
= 4x + 2y + 4z
iii. (14x2 + 8xy + 3y2) – (26x2 – 8xy – 17y2)
= 14x2 + 8xy + 3y2 – 26x2 + 8xy + 17y2
= (14x2 – 26x2) + (8xy + 8xy) + (3y2 + 17y2)
= -12x2 + 16xy + 20y2
iv. (6x2 + 7xy + 16y2) – (16x2 – 17xy)
= 6x2 + 7xy + 16y2 – 16x2 + 17xy
= (6x2 – 16x2) + (7xy + 17xy) + 16y2
= -10x2 + 24xy + 16y2
v. (4x + 16z) – (19y – 14z + 16x)
= 4x + 16z – 19y + 14z – 16x
= (4x – 16x) – 19y + (16z + 14z)
= -12x – 19y + 30z