(三道)请写出过程,..TAT...x2:平方;x4:四次方.1.3a2+ab-2b2=0(a≠0,b≠0),求a/b-b/a-(a2+b2)/ab2.设x=(根号5-1)/2,求x4+x2+2x-1的值3.计算(x+y+z)(-x+y+z)(x-y+z)(x+y-z)

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(三道)请写出过程,..TAT...x2:平方;x4:四次方.1.3a2+ab-2b2=0(a≠0,b≠0),求a/b-b/a-(a2+b2)/ab2.设x=(根号5-1)/2,求x4+x2+2x-1的值3.计算(x+y+z)(-x+y+z)(x-y+z)(x+y-z)
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(三道)请写出过程,..TAT...x2:平方;x4:四次方.1.3a2+ab-2b2=0(a≠0,b≠0),求a/b-b/a-(a2+b2)/ab2.设x=(根号5-1)/2,求x4+x2+2x-1的值3.计算(x+y+z)(-x+y+z)(x-y+z)(x+y-z)
(三道)
请写出过程,..TAT...
x2:平方;x4:四次方.
1.3a2+ab-2b2=0(a≠0,b≠0),求a/b-b/a-(a2+b2)/ab
2.设x=(根号5-1)/2,求x4+x2+2x-1的值
3.计算(x+y+z)(-x+y+z)(x-y+z)(x+y-z)

(三道)请写出过程,..TAT...x2:平方;x4:四次方.1.3a2+ab-2b2=0(a≠0,b≠0),求a/b-b/a-(a2+b2)/ab2.设x=(根号5-1)/2,求x4+x2+2x-1的值3.计算(x+y+z)(-x+y+z)(x-y+z)(x+y-z)
第一题分解成(a+b)(3a-2b)=0
a=-b舍去,因为带入原式得a=b=0 令a=2k,b=3k算出原式=-3
也可以不用k直接a=2,b=3算无影响
第二题
x4+x2+2x-1=x4+(x-1)^2=(23-13√5)/4 貌似没简便方法,
第三题
(x+y+z)(x-y+z)(x+y-z)(y+z-x)
=(((x+z)^2-y^2)(y^2-(x-z)^2))
=y^2((x+z)^2+(x-z)^2)-y^4-(x+z)^2(x-z)^2
=y^2(2x^2+2z^2)-y^4-(x^2-z^2)^2
=2x^2y^2+2y^2z^2-y^4-x^4-z^4+2x^2z^2
=2x^2y^2+2y^2z^2+2x^2z^2-x^4-y^4-z^4 累死我了,呼呼,分给我吧