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问题: u,v满足v=根号下{(2u-v)/(2u 3v)} 根号下{(v-2u)/(4u 3v)} 2/3,求u^2-uv的值

解答:

根号下[(2u-v)/(2u+3v)]>=0;& 根号下[(v-2u)/(4u+3v)]>=0;& 2/3>0.
--->v>0
(2u-v)/(2u+3v)>=0--->u<-2/3*v;or u>=v/2.
(v-2u)/(4u+3v)>=0--->-3v/4<u=<v/2.
--->u=v/2--->2u-v=0;& v-2u=0
--->v=0+0+2/3=2/3:& u=v/2=1/3
--->u^2-uv=(1/3)^2-1/3*2/3=-1/9