Đáp án:
`a)` `x^2``+``5`
`b)` `5x^3` `-` `24x^2``+``13x``-``4`
Giải thích các bước giải:
`a``)` `(x+1)^2``-``2(x-1)``(x+2)`
`=` `x^2``+``2x``+``1` `-` `(2x-2)``(x+2)`
`=` `x^2``+``2x``+``1` `-` `(2x^2+4x-2x-4)`
`=``x^2``+``2x``+``1``-2x^2``-4x``+``2x``+``4`
`=` `x^2``+``5`
`b``)` `2x``(2x-1)^2``-``4x``(2x+1)^2``-``3x``(x+3)``(x-3)`
`=` `2x``(4x^2-4x+1)``-``4``(4x^2+4x+1)``-``3x``(x^2-9)`
`=` `8x^3``-``8x^2``+``2x``-``16x^2``-``16x``-``4``-``3x^3``+``27x`
`=` `5x^3` `-` `24x^2``+``13x``-``4`
