Answer:
Step-by-step explanation:
Combine like terms. Like terms have same variable with same power
a) (2xy + 4x) + (15xy - 5x) = 2xy + 15xy + 4x - 5x
= 17xy - x
b) (6a + 4b² - 3) + (3b² - 5) = 6a + 4b² + 3b² - 3 - 5
= 6a + 7b² - 8
c) (4x³ - 3x² +4x) + (8x² - 5x ) = 4x³ - 3x² + 8x² + 4x - 5x
= 4x³ + 5x² - x
d) (7b - 6a + 9y) - (12b + 5a - 2y) =
In subtraction, add the additive inverse of (12b + 5a - 2y)
additive inverse = - 12b - 5a + 2y
(7b - 6a + 9y) - (12b + 5a - 2y) = 7b - 6a + 9y -12b -5a + 2y
= 7b - 12b -6a - 5a + 9y + 2y
= -5b - 11a + 11y
e) (2x² + 7x - 2 + 9y) - (13x + 4x² + 5 - 6y)
Additive inverse of 13x + 4x² + 5 - 6y = -13x + 4x² - 5 + 6y
(2x² + 7x - 2 + 9y) - (13x + 4x² + 5 - 6y)= 2x² + 7x - 2 + 9y -13x - 4x² -5 +6y
= 2x² - 4x² + 7x -13x -2 - 5 + 9y + 6y
= -2x² - 6x - 7 + 15y
