Вправи: 1093

1093. Розв’яжіть систему рівнянь

в) 13(x + y) – 14(x – y) = 5, •12 4(x + y) – 3(x – y) = 60,

112(x + y) + 13(x – y) = 6; •12 (x + y) + 4(x – y) = 72;

4x + 4y – 3x + 3y = 60, x + 7y = 60, x = 60 – 7y,

x + y + 4x – 4y = 72; 5x – 3y = 72; 5(60 – 7y) – 3y = 72;

300 – 35y – 3y = 72; –38y = –228; y = 6; ⇒ x = 60 – 7 • 6 = 60 – 42 = 18.