~ Bạn tham khảo ~
`2, 3x(x-5)-(2x-1)^2`
`= 3x^2-15x-4x^2+4x-1`
`= -x^2-11x-1`
`3, (2x+3)^2 + (x+3)(2-x)`
`= 4x^2+12x+9+2x-x^2+6-3x`
`= 3x^2+11x+15`
`4, (x+1)(x^2-x+1)-x^3+8`
`= x^3+1-x^3+8`
`= 9`
`5, (x+1)^3 - (x+2)(x-2)`
`= x^3+3x^2+3x+1-x^2+4`
`= x^3+2x^2+3x+5`