X2-5x+3=0; {x+y=7,5x-7y=11

1)x^2 -5x +3 = 0 D = 25 - 12 = 13 x = 5-[latex] \sqrt{13} [/latex] / 2 x = 5+ [latex] \sqrt{13} [/latex]/2 2) x=7-y 5(7-y) - 7y = 11 35 - 5y -7y=11 -12y = -24 y=2 x+2 = 7 x=5 (5;2)