Tính giúp mik với

a) (2x-5).(x+1)-(x-4).(x+4)

b) (2x-3).(2x+3)-(2x+1)²

c) (x-2)³+(x-1)³

d) (3x-2).(4x+5)-(2x+1)²

Ai lm nhanh nhất mik cho 5 saooooooooo

Đáp án+Giải thích các bước giải:

`a)`

`(2x-5)(x+1)-(x-4)(x+4)`

`=2x^2+2x-5x-5-x^2+16`

`=(2x^2-x^2)+(2x-5x)+(-5+16)`

`=x^2-3x+11`

`b)`

`(2x-3)(2x+3)-(2x+1)^2`

`=4x^2-9-4x^2-4x-1`

`=(4x^2-4x^2)-4x+(-9-1)`

`=-4x-10`

`c)`

`(x-2)^3+(x-1)^3`

`=x^3-6x^2+12x-8+x^3-3x^2+3x-1`

`=(x^3+x^3)+(-6x^2-3x^2)+(12x+3x)+(-8-1)`

`=2x^3-9x^2+15x-9`

`d)`

`(3x-2)(4x+5)-(2x+1)^2`

`=12x^2+15x-8x-10-4x^2-4x-1`

`=(12x^2-4x^2)+(15x-8x-4x)+(-10-1)`

`=8x^2+3x-11`

`#ld`