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a fost răspuns

x-y=9
xy=10, x²+y²=?

Răspuns :

Angelicus
[tex](x-y)^2=9^2[/tex]
[tex]x^2-2xy+y^2=81[/tex]
[tex] x^{2} -2*10+y^2=81[/tex]
[tex] x^{2} -20+y^2=81 [/tex]
[tex] x^{2} +y^2=81+20[/tex]
[tex] x^{2} +y^2=101[/tex]