Question

daca. x patrat+y patrat =58 si x-y=4 calculati x+y. Ajutor dau coroana

Answer 1

x^2+y^2=58; x-y=4 => y=x-4 => x^2+(x-4)^2=58 <=> x^2+x^2-8x+16=58 <=> 2x^2-8x-42=0, impartim prin 2 => x^2-4x-21=0; delta=16+84=100; x1=(4-10)/2=-3; x2=(4+10)/2=7 => y1=-3-4=-7; y2=7-4=3. Deci, x+y=-10 sau 10.