a,(3x+7).(2x+3)-(3x-5).(2x+11) b,(2x+1).(x-3)-(x+4).(2x-5) c,(6x-1).(2-x)+(3x+5).(2x-1) d,3.(x-2).(x+4)-(3x+1).(x+3) ĐÂY LÀ BÀI RÚT GỌN BIỂU THỨC Ạ EM

`a,(3x+7).(2x+3)-(3x-5).(2x+11)`

` = (6x^2 + 9x + 14x + 21) – (6x^2 + 33x – 10x – 55)`

` = 6x^2 + 9x + 14x + 21 – 6x^2 – 33x + 10x + 55`

` = (6x^2 – 6x^2) + (9x+14x – 33x+10x) + (21+55)`

` = 76`

`b,(2x+1).(x-3)-(x+4).(2x-5)`

` = (2x^2 – 6x + x – 3)-(2x^2 – 5x + 8x-20)`

` = 2x^2 – 6x + x – 3 – 2x^2 + 5x – 8x + 20`

` = (2x^2- 2x^2) + (-6x + x + 5x-8x) + (20-3)`

` = -8x + 17`

`c,(6x-1).(2-x)+(3x+5).(2x-1)`

` = (12x – 6x^2 – 2 + x) + (6x^2 – 3x + 10x – 5)`

` = 12x – 6x^2 – 2 + x + 6x^2 – 3x + 10x – 5`

` = (6x^2- 6x^2)+ (12x + x – 3x + 10x) – (2+5)`

` = 20x – 7`

`d,3.(x-2).(x+4)-(3x+1).(x+3)`

` = (3x-6).(x+4) – (3x+1).(x+3)`

` = (3x^2 + 12x – 6x – 24) – (3x^2 + 9x + x + 3)`

` = 3x^2 + 12x-6x-24 – 3x^2 – 9x-x-3`

` = (3x^2 – 3x^2) + (12x-6x – 9x-x) – (24+3)`

` = -4x – 27`