Question

Daca x+y=12 si x^2 - y^2=48 daterminati valorile lui x,y

Answer 1

x^2-y2=(x+y)(x-y)⇒
48=12*(x-y) ⇒
x-y=48:12=4
si acum am sistemul
x+y=12
x-y=4
le adun si obtin
2x=16, x=8 si 
y=12-8=4