设函数Z=f(x,y)=xy/x2+y2,则下列个结论中不正确的是()
设函数Z=f(x,y)=xy/x2+y2,则下列个结论中不正确的是()
A f(1,y/x)=xy/x2+y2B f(1,x/y)=xy/x2+y2C f(1/x,1/y)=xy/x2+y2 D f(x+y,x-y)=xy/x2+y2为什么选D,求详解
A f(1,y/x)=xy/x2+y2B f(1,x/y)=xy/x2+y2C f(1/x,1/y)=xy/x2+y2 D f(x+y,x-y)=xy/x2+y2为什么选D,求详解
数学人气:408 ℃时间:2020-07-01 00:25:08
优质解答
A,把1,y/x代入,得f(1,y/x) = (y/x) / (1 + y^2/x^2) = xy / (x^2 + y^2)B.和A一样的方式,只是以x/y代y/xC.把1/x,1/y代入,f(1/x,1/y) = (1/xy) / ( 1/x^2 + 1/y^2) = xy / (x^2 + y^2)所以A,B,C都成立.D.f(x+y,x-y)= ...
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