(x-y)(x+1)=41[tex]
\left \{ {{x-y=1} \atop { x^{2} - y^{2} =41}} \right. [/tex] ⇒
[tex] \left \{ {{x-y=1} \atop {(x-y)(x+y)=41}} \right. [/tex]⇒
[tex] \left \{ {{x-y=1} \atop {x+y=41}} \right. [/tex], adunam cela 2 ec. si avem 2x=42 I :2 ⇒ x=21, din x-y=1 ⇒21-y=1⇒y=20 deci solutia; x=21 ; y=20
