Question

решите систему уравнений 7x-5y = 8 x+y = 1 целая 3/35

Answer 1

$left { {{7x-5y=8} atop {x+y=1 frac{3}{35} }} right. left { {{7x-5y=8} atop {5x+5y=5 frac{3}{7} }} right. \\ 7x+5x=8+5 frac{3}{7} \\ 12x=13 frac{3}{7} = frac{94}{7} \\ x= frac{94}{12*7} = frac{47}{6*7} = frac{47}{42} \\ 7* frac{47}{42} -5y=8\\ frac{47}{6} -5y=8\\ 5y= frac{47}{6} -8= frac{47-8*6}{6} =- frac{1}{6} \\ y= -frac{1}{6*5} =- frac{1}{30}$