Question

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

Answer 1

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

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

Ответ: $(4\frac{7}{13};\ \frac{2}{13})$