Hướng dẫn trả lời:
a) `3acdot(a + b) + 2cdot(a + b)^2`
`= [3a + 2cdot(a + b)]cdot(a + b)`
`= (3a + 2a + 2b)cdot(a + b)`
`= (5a + 2b)cdot(a + b)`
b) `-2acdot(2a - 1) - 1cdot(1 - 2a)`
`= -2acdot(2a - 1) - 1cdot-(2a - 1)`
`= -2acdot(2a - 1) + 1cdot(2a - 1)`
`= (-2a + 1)cdot(2a - 1)`
`= -(2a - 1)cdot(2a - 1)`
`= -(2a - 1)^2`
c) `2cdot(x - 1)^2 - (x - 1)^3`
`= [2 - (x - 1)]cdot(x - 1)^2`
`= (2 - x + 1)cdot(x - 1)^2`
`= (- x + 3)cdot(x - 1)^2`
`= - (x - 3)cdot(x - 1)^2`
d) `5cdot(x - 1)^3 - 10cdot(1 - x)^2`
`= 5cdot(x - 1)^3 - 10cdot(x - 1)^2`
`= [5cdot(x - 1) - 10]cdot(x - 1)^2`
`= (5x - 5 - 10)cdot(x - 1)^2`
`= (5x - 15)cdot(x - 1)^2`
`= 5cdot(x - 3)cdot(x - 1)^2`
Đáp án:
a) `= (5a + 2b)cdot(a + b)`
b) `= - (2a - 1)^2`
c) `= - (x - 3)cdot(x - 1)^2`
d) `= 5cdot(x - 3)cdot(x - 1)^2`
