Question

Решите систему уравнений:

$\left \{ {{x-4y = 7,3}\atop {2x-y=7}} \right.$

Answer 1

$\displaystyle\bf\\\left \{ {{x-4y=7,3} \atop {2x-y=7} \ |\cdot (-4)} \right. \\\\\\+\left \{ {{x-4y=7,3} \atop {-8x+4y=-28}} \right. \\-----------\\-7x=-20,7\\\\x=2\frac{67}{70} \\\\y=2x-7=2\cdot2\frac{67}{70} -7=5\frac{32}{35} -7=-1\frac{3}{35}$