Question

решите систему уравнений: 2х-7у=8, х+3у=5 методом подстановки

Answer 1

$left { {{2x-7y=8} atop {x+3y=5}} right. \\ left { {{2*(-3y+5)-7y=8} atop {x=-3y+5}} right. \\ left { {{-6y+10-7y=8} atop {x=-3y+5}} right. \\ left { {{-13y=8-10} atop {x=-3y+5}} right. \\ left { {{-13y=-2} atop {x=-3y+5}} right. \\ left { {{13y=2} atop {x=-3y+5}} right. \\ left { {{y=frac{2}{13}} atop {x=-3*frac{2}{13}+5}} right. \\ left { {{y=frac{2}{13}} atop {x=-frac{6}{13}+5}} right.$

$left { {{y=frac{2}{13}} atop {x=4frac{7}{13}}} right. \\ left { {{x=4frac{7}{13}} atop {y=frac{2}{13}}} right.$

Ответ: $(4frac{7}{13}; frac{2}{13})$