Question

Решите систему уравнений. Люблю:)

Answer 1

x+y=t
x-y=z
$\left \{ {{3t-4z=5}|*(-4) \atop {4t-3z=9}|*3} \right. \\ + \left \{ {{-12t+16z=-20} \atop {12t-9z=27}} \right. \\ 7z=7 \\ z=1 \\ t= \frac{9+3z}{4} =3 \\ + \left \{ {{x+y=3} \atop {x-y=1}} \right. \\ 2x=4 \\ x=2 \\ y=3-x=3-2=1$
Ответ (2;1)