初二数学题(x-y/x+2y)的立方

来源:学生作业帮助网 编辑:六六作业网 时间:2024/05/15 09:04:39
初二数学题(x-y/x+2y)的立方初二数学题(x-y/x+2y)的立方初二数学题(x-y/x+2y)的立方x^3-3x^2y+3xy^2-y^3____________________x^3+6x^

初二数学题(x-y/x+2y)的立方
初二数学题(x-y/x+2y)的立方

初二数学题(x-y/x+2y)的立方
x^3-3x^2y+3xy^2-y^3
____________________
x^3+6x^2y+6xy^2+8y^3

[(x-y)/(x+2y)]^3
=(x-y)^3/(x+2y)^3
=[(x-y)^2*(x-y)]/[(x+2y)^2*(x+2y)]
=[(x^2-2xy+y^2)^2*(x-y)]/[(x^2+4xy+4y^2)^2*(x+2y)]
=(x^3-x^2y+xy^2-y^3-2x^2y+2xy^2)/(x^3+2x^2y+4xy^2+8y^3+4x^2y+8xy^2)
=(x^3-3x^2y+3xy^2-y^3)/(x^3+6x^2y+12xy^2+8y^3)