Question

规定A☆B=A+B/A-B,已知x☆5☆1=6,求x=?

已知A、B是两个数，规定A☆B=A+B/A-B,已知x☆（5☆1）=6,求x=?

Answer 1

x☆5☆1
=[(x+5)/(x-5)]☆1
={[(x+5)/(x-5)]+1}/{[(x+5)/(x-5)]-1}
=2x/10=x/5
x/5=6
x=30

x☆(5☆1)
=x☆[(5+1)/(5-1)]
=x☆(3/2)
=(x+3/2)/(x-3/2)

(x+3/2)/(x-3/2)=6
x+3/2=6x-9
x=21/10
检验：……

Answer 2

x☆5☆1=6
(x☆5+1)/(x☆5-1)=6
x☆5=7/5
(x+5)/(x-5)=7/5
x=30

Answer 3

x=30

x☆5☆1=(x+5/x-5)☆1
=〔（x+5/x-5)+1〕/〔(x+5/x-5)-1〕
=2x/10
=6

2x/10=6
2x=60
x=30

Answer 4

x☆5=7/5
x=30