代数式ax²+px+q,当x=1时,它的值是0;当x=-2时,它的值是5;当x=3时,它的值是-15.a＋p＋q=0①4a-2p＋q=5②9a＋3p＋q=-15③②-①,得3a-3p=5④③-①,得8a＋2p=-15⑤④×2＋⑤×3,得30a=-35a=-7/6代入④,得p=-17/6从而...