分解因式:(ax-by)三次方+(by-cz)三次方-(ax-cz)三次方
分解因式:(ax-by)三次方+(by-cz)三次方-(ax-cz)三次方
原式为:(ax-by)³+(by-cz)³-(ax-cz)³
=[(ax-by)+(by-cz)][(ax-by)²-(ax-by)(by-cz)+(by-cz)²]-(ax-cz)³
=(ax-cz)[(ax-by)²-(ax-by)(by-cz)+(by-cz)²]-(ax-cz)³
=(ax-cz)[(ax-by)²-(ax-by)(by-cz)+(by-cz)²-(ax-cz)²]
=(ax-cz)[(ax-by)(ax-by-by+cz)+(by-cz+ax-cz)(by-ax)]
=(ax-cz)[(ax-by)(ax-2by+cz)-(ax+by-2cz)(ax-by)]
=(ax-cz)[(ax-by)(ax-2by+cz-ax-by+2cz)]
=(ax-cz)(ax-by)(3cz-3by)
=3(ax-cz)(ax-by)(cz-by)
原理:A³+B³=(A+B)(A²-AB+B²)
A²-B²=(A+B)(A-B)
我a=ax;b=by;c=cz;代替哈;
(a+b)^3+(b-c)^3-(a-c)^3
=a^3+3ab^2-3a^2b-c^3+b^3+3bc^2-3b^2c-c^3-a^3-3ac^2+3a^2c+c^3
=3{ab(b-a)+bc(c-b)+ac(a-c)}
原式=[(ax-by)³+(by-cz)³]-(ax-cz)³ 运用立方和公式 x³+y³=(x+y)(x²-xy+y²)=[(ax-by)+(by-cz)][(ax-by)²-(ax-by)(by-cz)+(by-cz)²]-(ax-cz)³=(ax-by+by-cz)[(ax-...