Đáp án+Giải thích các bước giải:
`a)(x-2)^2 .(y+3)^2`
`=(x^2-4x+4)(y^2+6y+9)`
`=x^2 y^2+6x^2 y+9x^2-4xy^2-24xy-36x+4y^2+24y+36`
`=x^2 y^2+6x^2 y-4xy^2+9x^2+4y^2-24xy-36x+24y+36`
`b)(2x-1)^2 .(2y-3)^2`
`=(4x^2-4x+1)(4y^2-12y+9)`
`=16x^2 y^2-48x^2 y+36x^2-16xy^2+48xy-36x+4y^2-12y+9`
`=16x^2 y^2-48x^2 y-16xy^2+36x^2+4y^2+48xy-36x-12y+9`
`c)(x-5)(x+5)`
`=x^2-25`
`d)(2x-1)^2+(2x+1)^2+(2x-1)(2x+1)`
`=4x^2-4x+1+4x^2+4x+1+4x^2-1`
`=12x^2+1`