281. ա){x + y — 7 = 0{x2 + xy + y2 = 43-y = x — 7y = 7 — xx2 + xy + y = 43×2 + x(7 — x) + (7 — x)2 = 43×2 — 7x — x2 + 49 — 14x + x2 = 43&#2…