標題:
發問:
(2x+y)^3+(x+2y)^3
最佳解答:
(2x+y)^3+(x+2y)^3 = (2x)^3 + 3(2x)^2 y + 3(2x)y^2 + y^3 + x^3 + 3x^2 (2y) + 3(x)(2y)^2 + (2y)^3 = 8x^3 + 12x^2 y + 6xy^2 + y^3 + x^3 + 6x^2 y + 12xy^2 + 8y^3 = 9x^3 + 18x^2 y + 18xy^2 + 9y^3 2011-09-07 23:01:02 補充： (2x+y)^3+(x+2y)^3 = (2x+y+x+2y)[(2x+y)^2 - (2x+y)(x+2y) + (x+2y)^2] = 3(x+y)(4x^2 + 4xy + y^2 - 2x^2 - 4xy - xy - 2y^2 + x^2 + 4xy + 4y^2) = 3(x+y)(3x^2 + 4xy + 3y^2)
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中2數 (2x+y)^3+(x+2y)^3發問:
(2x+y)^3+(x+2y)^3
最佳解答:
(2x+y)^3+(x+2y)^3 = (2x)^3 + 3(2x)^2 y + 3(2x)y^2 + y^3 + x^3 + 3x^2 (2y) + 3(x)(2y)^2 + (2y)^3 = 8x^3 + 12x^2 y + 6xy^2 + y^3 + x^3 + 6x^2 y + 12xy^2 + 8y^3 = 9x^3 + 18x^2 y + 18xy^2 + 9y^3 2011-09-07 23:01:02 補充： (2x+y)^3+(x+2y)^3 = (2x+y+x+2y)[(2x+y)^2 - (2x+y)(x+2y) + (x+2y)^2] = 3(x+y)(4x^2 + 4xy + y^2 - 2x^2 - 4xy - xy - 2y^2 + x^2 + 4xy + 4y^2) = 3(x+y)(3x^2 + 4xy + 3y^2)
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