已知x加y等于6,xy等于8,求分式x分之y加y分 - 知识问答

已知x加y等于6,xy等于8,求分式x分之y加y分之x的值

1个回答

x+y=6,xy=8
y/x+x/y
=y^2/xy+x^2/xy
=(x^2+y^2)/xy
=(x^2+2xy+y^2-2xy)/xy
=[(x+y)^2-2xy]/xy
=(x+y)^2/xy-2xy/xy
=6^2/8-2
=9/2-2
=5/2

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