解答
化简 (x+y+z)3−(x−y−z)3−6(x+y+z)(x−y−z)(y+z)
解答
24yz2+8z3+24y2z+8y3
求解步骤
(x+y+z)3−(x−y−z)3−6(x+y+z)(x−y−z)(y+z)
展开 (x+y+z)3:x3+3x2y+3x2z+3xz2+3yz2+3xy2+z3+3y2z+6xyz+y3
=x3+3x2y+3x2z+3xz2+3yz2+3xy2+z3+3y2z+6xyz+y3−(x−y−z)3−6(x+y+z)(x−y−z)(y+z)
展开 −(x−y−z)3:−x3+3x2y+3x2z−3xz2+3yz2−3xy2+z3+3y2z−6xyz+y3
=x3+3x2y+3x2z+3xz2+3yz2+3xy2+z3+3y2z+6xyz+y3−x3+3x2y+3x2z−3xz2+3yz2−3xy2+z3+3y2z−6xyz+y3−6(x+y+z)(x−y−z)(y+z)
展开 −6(x+y+z)(x−y−z)(y+z):−6x2y+18y2z+18yz2+6y3+6z3−6x2z
=x3+3x2y+3x2z+3xz2+3yz2+3xy2+z3+3y2z+6xyz+y3−x3+3x2y+3x2z−3xz2+3yz2−3xy2+z3+3y2z−6xyz+y3−6x2y+18y2z+18yz2+6y3+6z3−6x2z
对同类项分组=x3−x3+3x2y+3x2y−6x2y+3x2z+3x2z−6x2z+3xz2−3xz2+3yz2+3yz2+18yz2+3xy2−3xy2+z3+6z3+z3+3y2z+3y2z+18y2z+6xyz−6xyz+y3+6y3+y3
同类项相加:x3−x3=0=3x2y+3x2y−6x2y+3x2z+3x2z−6x2z+3xz2−3xz2+3yz2+3yz2+18yz2+3xy2−3xy2+z3+6z3+z3+3y2z+3y2z+18y2z+6xyz−6xyz+y3+6y3+y3
同类项相加:3x2y+3x2y−6x2y=0=3x2z+3x2z−6x2z+3xz2−3xz2+3yz2+3yz2+18yz2+3xy2−3xy2+z3+6z3+z3+3y2z+3y2z+18y2z+6xyz−6xyz+y3+6y3+y3
同类项相加:3x2z+3x2z−6x2z=0=3xz2−3xz2+3yz2+3yz2+18yz2+3xy2−3xy2+z3+6z3+z3+3y2z+3y2z+18y2z+6xyz−6xyz+y3+6y3+y3
同类项相加:3xz2−3xz2=0=3yz2+3yz2+18yz2+3xy2−3xy2+z3+6z3+z3+3y2z+3y2z+18y2z+6xyz−6xyz+y3+6y3+y3
同类项相加:3yz2+3yz2+18yz2=24yz2=24yz2+3xy2−3xy2+z3+6z3+z3+3y2z+3y2z+18y2z+6xyz−6xyz+y3+6y3+y3
同类项相加:3xy2−3xy2=0=24yz2+z3+6z3+z3+3y2z+3y2z+18y2z+6xyz−6xyz+y3+6y3+y3
同类项相加:z3+6z3+z3=8z3=24yz2+8z3+3y2z+3y2z+18y2z+6xyz−6xyz+y3+6y3+y3
同类项相加:3y2z+3y2z+18y2z=24y2z=24yz2+8z3+24y2z+6xyz−6xyz+y3+6y3+y3
同类项相加:6xyz−6xyz=0=24yz2+8z3+24y2z+y3+6y3+y3
同类项相加:y3+6y3+y3=8y3=24yz2+8z3+24y2z+8y3