Question

Розв’яжiть методом пiдстановки систему piвнянь :

{4х+3у=7;
{2х+у=5.

Answer 1

$\displaystyle\bf\\\left \{ {{4x+3y=7} \atop {2x+y=5}} \right. \\\\\\\left \{ {{4x+3y=7} \atop {y=5-2x}} \right.\\\\\\\left \{ {{4x+3\cdot(5-2x)=7} \atop {y=5-2x}} \right.\\\\\\\left \{ {{4x+15-6x=7} \atop {y=5-2x}} \right. \\\\\\\left \{ {{-2x=-8} \atop {y=5-2x}} \right. \\\\\\\left \{ {{x=4} \atop {y=5-2\cdot 4}} \right. \\\\\\\left \{ {{x=4} \atop {y=-3}} \right. \\\\\\Otvet: \ \Big(4 \ ; \ -3\Big)$