设f(xy,x-y)=x²+y²,则f(x,y)=?设f(x-y,x+y)=xy,求f(x,y) 这两道题是同一种题型 教教呀
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![设f(xy,x-y)=x²+y²,则f(x,y)=?设f(x-y,x+y)=xy,求f(x,y) 这两道题是同一种题型 教教呀](/uploads/image/z/7217708-68-8.jpg?t=%E8%AE%BEf%28xy%2Cx-y%29%3Dx%26%23178%3B%2By%26%23178%3B%2C%E5%88%99f%28x%2Cy%29%3D%3F%E8%AE%BEf%28x-y%2Cx%2By%29%3Dxy%2C%E6%B1%82f%28x%2Cy%29+%E8%BF%99%E4%B8%A4%E9%81%93%E9%A2%98%E6%98%AF%E5%90%8C%E4%B8%80%E7%A7%8D%E9%A2%98%E5%9E%8B+%E6%95%99%E6%95%99%E5%91%80)
设f(xy,x-y)=x²+y²,则f(x,y)=?设f(x-y,x+y)=xy,求f(x,y) 这两道题是同一种题型 教教呀
设f(xy,x-y)=x²+y²,则f(x,y)=?
设f(x-y,x+y)=xy,求f(x,y) 这两道题是同一种题型 教教呀
设f(xy,x-y)=x²+y²,则f(x,y)=?设f(x-y,x+y)=xy,求f(x,y) 这两道题是同一种题型 教教呀
f(xy,x-y)=x²+y²=-2xy+(x-y)^2
因此f(x,y)=-2x+y^2
f(x-y,x+y)=xy=1/4[(x+y)+(x-y)][(x+y)-(x-y)]
f(x,y)=1/4(y+x)(y-x)=1/4(y^2-x^2)