高校问答癫佬正传百度云链接:因式分解 27X3+9X2Y+XY2+1/27Y3
来源：百度文库 编辑：高校问答 时间：2024/05/07 13:30:56
X3是X的立方 ，X2是X的平方，Y3是Y的立方
=[(3X)^3+(Y/3)^3=(3X+Y/3)(9X^2-XY+Y^2/9)是怎么弄的啊
=[(3X)^3+(Y/3)^3=(3X+Y/3)(9X^2-XY+Y^2/9)是怎么弄的啊
27X3+9X2Y+XY2+1/27Y3
=(27X3+1/27Y3)+(9X2Y+XY2)
=[(3X)^3+(Y/3)^3]+XY(9X+Y)
=(3X+Y/3)(9X^2-XY+Y^2/9)+XY(9X+Y)
=1/3(9X+Y)(9X^2-XY+Y^2/9)+XY(9X+Y)
=(9X+Y)(3X^2-XY/3+Y^2/27+XY)
=(9X+Y)(81X^2+18XY+Y^2)/27
=1/27*(9X+Y)^3