a2—b2=2ab求a—b/a+b

a2—b2=2ab
(a/b)²-2(a/b)-1=0
a/b=(2±√8)/2=1±√2
(1)当a/b=1+√2时
(a-b)/(a+b)=[(a/b)-1]/[(a/b)+1)]=√2/(√2+2)=√2-1
(2)当a/b=1-√2时
(a-b)/(a+b)=[(a/b)-1]/[(a/b)+1)]=-√2/(2-√2)=√2+1
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b/a

a²-b²=2ab
1-b²/a²=2b/a
b²/a²+2b/a-1=0
b/a=-1±√2
(a-b)/(a+b)
=(a-b)²/[(a+b)(a-b)]
=（a²+b²-2ab）/(a²-b²） （a²-2ab=b²）
=2b²/2ab
=b/a
=-1±√2

设a-b/a+b=x
a2-b-=2ab a-b/a+b=x 两个方程联合，可得出a/b=2+x
a-b/a+b=x a/b=2+x 两个方程联合，可得出x=-1±根号2
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