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dimitar


BDT x,y thuôc [0,1]
cm căn(1+x^2) +căn(1+y^2) +căn((1-x)^2+(1-y)^2) >=1+căn5 .(1-xy)
cm căn(1+x^2) +căn(1+y^2) +căn((1-x)^2+(1-y)^2) >=1+căn5 .(1-xy)
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