24、有A、B、C、D、E五個隊(duì)分在同一小組進(jìn)行單循環(huán)足球比賽(每兩隊(duì)只進(jìn)行一場比賽),為爭奪出線權(quán),比賽規(guī)則規(guī)定:勝一場得3分,平一場每隊(duì)各得1分,負(fù)一場得0分,小組賽結(jié)束后,小組中名次在前的兩個隊(duì)出線,請你解答下列問題:
(1)小組賽結(jié)束后,若A隊(duì)的積分為9分時,設(shè)A隊(duì)勝x場,平y(tǒng)場,則3x+y=
9
,其中x,y為非負(fù)整數(shù),且滿足不等式x+y≤
4
,根據(jù)這些相等關(guān)系和不等關(guān)系,可以確定x=
3
,y=
0
.
(2)小組賽結(jié)束后,設(shè)5個隊(duì)積分總和為n,則滿足
20
≤n≤
30
.
(3)小組賽結(jié)束后,若A隊(duì)的積分為10分,A隊(duì)能出線嗎?請你對A隊(duì)能否出線做出分析.