作业帮试证函数F(x,y) = ln x ⋅ ln y满足关系式 F(xy,uv) = F(x,u) + F(x,v) + F( y,u) + F( y,v) .
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试证函数F(x,y) = ln x ⋅ ln y满足关系式 F(xy,uv) = F(x,u) + F(x,v) + F( y,u) + F( y,v) .
试证函数F(x,y) = ln x ⋅ ln y满足关系式 F(xy,uv) = F(x,u) + F(x,v) + F( y,u) + F( y,v) .
试证函数F(x,y) = ln x ⋅ ln y满足关系式 F(xy,uv) = F(x,u) + F(x,v) + F( y,u) + F( y,v) .
证
F(xy,uv) = ln(xy) ⋅ ln(uv) = (ln x + ln y) ⋅ (ln u + ln v)
= ln x ⋅ ln u + ln x ⋅ ln v + ln y ⋅ ln u + ln y ⋅ ln v
= F(x,u) + F(x,v) + F( y,u) + F( y,v) .