七年级下数学经典例题 (259)
七年级下数学经典例题(X — y = 1x + 3y + z = 10 x — 2y — z = —2Cx-y = 1 ① { x + 3y + z = 10 ② \x — 2y — z = _2 ③
七年级下数学经典例题 (259)