已知x=1/2 y=1/3 z=1/4 则(xx+yy-zz+2xy)/(xx-yy+zz-2xz) 得多少?谁会这到题还有这到题:已知a=20002000/20012001,b=20012001/20022002c=200220002/20032003,比较a,b,c的大小.
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![已知x=1/2 y=1/3 z=1/4 则(xx+yy-zz+2xy)/(xx-yy+zz-2xz) 得多少?谁会这到题还有这到题:已知a=20002000/20012001,b=20012001/20022002c=200220002/20032003,比较a,b,c的大小.](/uploads/image/z/7608777-33-7.jpg?t=%E5%B7%B2%E7%9F%A5x%3D1%2F2+y%3D1%2F3+z%3D1%2F4+%E5%88%99%28xx%2Byy-zz%2B2xy%29%2F%28xx-yy%2Bzz-2xz%29+%E5%BE%97%E5%A4%9A%E5%B0%91%3F%E8%B0%81%E4%BC%9A%E8%BF%99%E5%88%B0%E9%A2%98%E8%BF%98%E6%9C%89%E8%BF%99%E5%88%B0%E9%A2%98%3A%E5%B7%B2%E7%9F%A5a%3D20002000%2F20012001%2Cb%3D20012001%2F20022002c%3D200220002%2F20032003%2C%E6%AF%94%E8%BE%83a%2Cb%2Cc%E7%9A%84%E5%A4%A7%E5%B0%8F.)
已知x=1/2 y=1/3 z=1/4 则(xx+yy-zz+2xy)/(xx-yy+zz-2xz) 得多少?谁会这到题还有这到题:已知a=20002000/20012001,b=20012001/20022002c=200220002/20032003,比较a,b,c的大小.
已知x=1/2 y=1/3 z=1/4 则(xx+yy-zz+2xy)/(xx-yy+zz-2xz) 得多少?
谁会这到题
还有这到题:已知a=20002000/20012001,b=20012001/20022002
c=200220002/20032003,比较a,b,c的大小.
已知x=1/2 y=1/3 z=1/4 则(xx+yy-zz+2xy)/(xx-yy+zz-2xz) 得多少?谁会这到题还有这到题:已知a=20002000/20012001,b=20012001/20022002c=200220002/20032003,比较a,b,c的大小.
x2+y2-z2+2xy/x2-y2+z2-2xz
=(x+y)2-z2/(x-z)2-y2
=(x+y-z)(x+y+z)/(x-y-z)(x-z+y)
=(x+y+z)/(x-y-z)
然后就是代入了
(xx+yy-zz+2xy)/(xx-yy+zz-2xz)
=[(x+y)^2-z^2]/[(x-z)^2-y^2]
=(x+y+z)(x+y-z)/(x-z+y)(x-z-y)
=(x+y+z)/(x-z-y)
=[(6+3+4)/12]/[(6-3-4)/12]
=-13
(X^2+Y^2-Z^2+2XY)(X^2-Y^2+Z^2-2XZ)
=[(X+Y)^2-Z^2]/[(X^2-Z^2)-Y^2]
=(X+Y+Z)(X+Y-Z)/(X-Z+Y)(X-Y-Z)
=(X+Y+Z)(/(X-Y-Z)
=(1/2+1/3+1/4)/(1/2-1/3-1/4)
=-13