(x+y+z)*(-x+y+z)*(x-y+z)*(x+y-z)=
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(x+y+z)*(-x+y+z)*(x-y+z)*(x+y-z)=
(x+y+z)*(-x+y+z)*(x-y+z)*(x+y-z) 因数 1 2 3 4
=(x+y+z)*(x+y-z)*(-x+y+z)*(x-y+z) 将因数1与因数4结合,因数2与因数3结合
= [(x+y)^2-z^2] *{[z-(x-y)][z+(x-y)]} 对因数1和4应用平方公式 (a+b)(a-b)=a^2 -b^2
= [(x+y)^2-z^2] [z^2- (x-y)^2] 再对因数2和3应用平方公式(a+b)(a-b)=a^2 -b^2
= (x^2+2xy+y^2-z^2) [z^2-(x-y)^2]
= - (x^2+y^2-z^2+2xy)(x^2+y^2-z^2-2xy) 再次使用平方公式(a+b)(a-b)=a^2 -b^2
= -[(x^2+y^2-z^2)^2-4x^2y^2]
= -[( x^2+y^2)^2+Z^4-2Z^2X^2-2Z^2Y^2-4x^2y^2]
= -(x^4+y^4 + Z^4- -2Z^2X^2-2Z^2Y^2-2x^2y^2 )
= 2Z^2X^2+2Z^2Y^2+2x^2y^2 -x^4-y^4 +-Z^4
=(x+y+z)*(x+y-z)*(-x+y+z)*(x-y+z) 将因数1与因数4结合,因数2与因数3结合
= [(x+y)^2-z^2] *{[z-(x-y)][z+(x-y)]} 对因数1和4应用平方公式 (a+b)(a-b)=a^2 -b^2
= [(x+y)^2-z^2] [z^2- (x-y)^2] 再对因数2和3应用平方公式(a+b)(a-b)=a^2 -b^2
= (x^2+2xy+y^2-z^2) [z^2-(x-y)^2]
= - (x^2+y^2-z^2+2xy)(x^2+y^2-z^2-2xy) 再次使用平方公式(a+b)(a-b)=a^2 -b^2
= -[(x^2+y^2-z^2)^2-4x^2y^2]
= -[( x^2+y^2)^2+Z^4-2Z^2X^2-2Z^2Y^2-4x^2y^2]
= -(x^4+y^4 + Z^4- -2Z^2X^2-2Z^2Y^2-2x^2y^2 )
= 2Z^2X^2+2Z^2Y^2+2x^2y^2 -x^4-y^4 +-Z^4
①(x+y+z)(-x+y+z)(x-y+z)(x+y-z)
x分之y+z=y分之z+x=z分之x+y(x+y+z不等于0),求x+y+z分之x+y-z
(x+y+z)*(-x+y+z)*(x-y+z)*(x+y-z)=
1.设X ,Y,Z 成等差数列,代数式(X-Z)*(X-Z)+ 4(X-Y)(Z-Y)=
(x-y+z)(x+y+z)等于多少.
计算:(x+y+z)(-x+y+z)(x-y+z)(x+y-z).
(x+y-z)(x-y+z)=
1998(z-y)+1999(y-z)+2000(z-x)=0 1998²(z-y)+1999²(y
x,y,z为正实数 x/(2x+y+z)+y/(x+2y+z)+z/(x+y+2z)
证明:(y+z-2x)3+(z+x-2y)3+(x+y-2z)3=3(y+z-2x)(z+x-2y)(x+y-2z).
X+Y+Z=?
已知x+y=3,y+z=4,x+z=5,则x+y+z等于( )