ѡB 㾦
ҪʵԪһη飬ؼҪĿ˼Ŀҳʵĵϵг飮
9A15 𰸡B
ѷĽ뷽ɵõabķ飬ⷽabٴa+ba-bֵ ⡿ ⣺
ǹxyķ
Ľ⣬
ǹxyķ
B15
Ľ⣬(a+b)(ab)ֵΪ( ) C16
D16
ࣨa+ba-b=-1+4-1-4=-15 ѡB 㾦
鷽ĽĸշĽ㷽еÿһǽؼ
10Сȥװ6ɫˮʺͱʼDZ4ʺ6ʼDZϵǮ22Ԫ ɹ1ʺ2ʼDZϵǮʣ34ԪϵǮ Ʒ(ֶ)ķУ A3 𰸡C
1ʵļ۸ΪxԪ1ʼDZļ۸ΪyԪݡ4ʺ6ʼDZϵǮ22Ԫijɹ1ʺ2ʼDZϵǮʣ34ԪɵóxyĶԪһη̣xyΪɵóۣɹaʺbʼDZܼ=ۡɵóabĶԪһη̣abΪɵóۣ ⡿
B4
C5
D6
1ʵļ۸ΪxԪ1ʼDZļ۸ΪyԪ ⣬ã4x+6y-22=x+2y+34 3x+4y=56y=14-xyΪ
3x 4?x4?x8?x12?x16????
y11y8y5y2????ɹaʺbʼDZ ٵx=4y=11ʱ4x+6y-22=60
4a+11b=60a=15-abΪ
11b 4?a4?
b4?ڵx=8y=8ʱ4x+6y-22=58 8a+8b=58a+b=abΪ ⣻
۵x=12y=5ʱ4x+6y-22=56
29 456?12a 5abΪ
12a+5b=56b=??a3 ?b4ܵx=16y=2ʱ4x+6y-22=54 16a+2b=54b=27-8a abΪ ?
?a1?a2?a3?? b19b11b3???5ֹ ѡC 㾦
˶Ԫһη̵ӦãϵȷгԪһηǽĹؼ
11һAʻBأǰ
1·Ϊͨ··Ϊٹ·֪3ͨ·ʻٶΪ60km/hڸٹ·ʻٶΪ100km/hAص
Bһʻ2.2hͨ·ٹ·ֱΪxkmykmзΪ
?x?2y?x?2y?2x?y?2x?y????A?x B?x C?x D?x yyyy??2.2??2.2??2.2??2.2?????10060?60100?60100?10060𰸡C
1A3صBһʻ2.2hɵóxyĶԪһη飬ý⣮ ⡿
ͨ·ٹ·ֱΪxkmykm⣬ã
ͨ·ٹ·ֱΪxkmykmͨ·ռ·̵
?2x?y? y?x??2.2??60100ʴΪC 㾦
ʵԪһη飬ϵȷгԪһηǽĹؼ
?a2?ab(a?b)12ʵab㡰ab??2ab?b(a?b)??x?y?3yxĽ⣬yxڣ 42?4?4?2?8Ƿ?3x?8y?14?2A3 𰸡D
B?3 C?1 D?6
ȸݷxyֵ¶㼴ɵó. ⡿
?x?y?3:?
3x?8y?14???x?2 y??1?2yx=?-1?2=?-1??2-2=-2-4=-6 ѡD
㾦
˶ԪһηĽⷨĹؼöԪһηĽⷨԼȷ¶㷨ڻͣ
13Ԫһη3x+y7( )飮 A0 𰸡C
ֱx=12м㼴ɵ ⡿ :3x+y=7 ε:y=7-3x
x=1ʱy=4;x=2ʱy=1 ̵ж ʱӦΪC 㾦
˶Ԫһη̵Ľ⣬һδֵ֪һδֵ֪.
B1
C2
D
14ĸȫһijκһСƴͼʾĴΣ֪ε196Сε4x,y?x?y?ʾεijͿĸʽвǣ
Ax?y?14 Cx2?y2?196 𰸡C
Bx?y?2 Dxy?48
ݴμСεֱμСεı߳Ȼxyֵжϸѡ ⡿
ãεı߳Ϊ14Сεı߳Ϊ2 x+y=14x?y=2