Question

Știind ca x^2-y^2=15 si x+y=5, Calculați (x-y)^2

Answer 1

[tex]x^2-y^2=15\\ (x-y)(x+y)=15\\ 5(x-y)=15\\ x-y=3|()^2\\ \boxed{(x-y)^2=9}[/tex]