(x+y)²=x²+y²+2xy=12xy+2xy=14xy
(x-y)²=x²+y²-2xy=12xy-2xy=10xy
x, y>0 x+y>0 , x+y=√(x+y)²=|x+y|=x+y=√(14xy) =√14*√xy
x>y asta lipsea adica un text corect ar fi fost x>y>0
x-y=√(x-y)²=|x-y|=x-y=√(10xy)=√10*√xy
de unde imediat indicatia 2
√14*√xy/(√10*√xy)=√14/√10=√2*√7/(√2*√5)=√7/√5=√7*√5/(√5*√5) =√35/5
