ʱ : 2017年中考数学真题分类解?一次方??及其应用 - 百度文库ϿʼĶ
2017пѧ
+ڵã3ab=5
16.15. 2017徭У3֣֪??x?a?x?2y?0Ƿ?Ľ⣬3a?b? .
?y?b?2x?y?5?x?aã3a-b=5. y?b?𰸣5.˼룬ӵã3x-y=5?
1С9֣ⷽ飺?
?x?y?5,.
?2x?3y?11˼·üӼԪԪ. ⣺١3 3x3y15ۣ ۣڣ x4.
x4٣ y1.
ýΪ??x=4,. ?y?1
2. 2017ɽ208֣ijũȥƻС200֣¼ʵʲ Ϊ225֣
׳5%С15%ũȥʵסСٶ֣
˼·ȥʾȥСײ200ֺͽ225з.
⣺ȥʵx֣Сy֣
??x?y?200, ?1?5%x?1?15%y?225.????????x?50,
?y?150.ࣨ1+5%50=52.5, 1+15%150=172.5. 𣺸ũȥʵ52.5֣С172.5. 3. 20178֣
2017пѧ
ijУ֯ľһƶÿĿ.ÿһ
21640ڶǰʣµȫȡͨһδʣµ3һ𣬸պִ9.ô鹲жٱ
˼·ؼδ֪ϵз. ⣺ÿx飬y飬У
?2y?16x?40??x?60?3֮ã ??y?15001??y?9x?40??3鹲1500.
4. 2017ݣ248֣498ʱ2017 ݹǹܣһ34Ӵһͬμ˱ߵĶԻ Һ16
2017пѧ
3ҵǡõڰְֵ
ݶԻݣ÷̵֪ʶõ. ˼·ҵ䣫䣽16ҵ3䣽34г鲢ü. ⣺x꣬y꣮ ?xy16?x6?ã? ?3x2y2342?y106꣬10 ?x???1,5. 172017˲С6֣ⲻʽ?2 ?2?1?x??4?3x.?˼·ݲʽʣȽһԪһβʽ⼯Ĺ֣ ⣺ɢٵ xݣ2ɢڵx<2ԣʽĽ⼯Ϊ-2x2
6. 232017238֣С8֣ijУƻ֯ʦ 300 ˲μһδ 6 ͳ 5 Сͳǡȫ֪ÿͳij˿λСͳ 17 1ÿͳÿСͳij˿λ2μӻ 30 ˣѧУڱó£ΪвμӻʦװɣСͳֵ
˼·(1)ÿͳÿСͳij˿ֱΪyˣx. ݢÿͳij˿λСͳ 17 6 ͳ
y?x?17 5 Сͳǡð300ȫװгԪһη???6y?5x?300
֮xy.(2)(1֪Ϊ11СͳΪaôͳΪ11
2017пѧ
aݡвμӻʦװɡװڻʦ330гʽ18a35(11a)30030⼯⼴ɡ ⣺1ÿСͳij˿λ x ͳij˿λ y
y?x?17???6y?5x?300x?18? ??y?35ÿͳij˿λΪ 35 ÿСͳij˿λΪ 18 5
2 a Сͳܽвμӻʦװɣ
418a35(11a)30030a3 7 17
a Ϊ 3СͳֵΪ 38
7. 202017ͺأ7֣ijרABƷ֪ڴǰ60AƷ 30BƷ1080Ԫ50AƷ10BƷ840ԪAB ƷͬԺij500AƷ450BƷһȲٻ1960Ԫ ˶ۣ ⣺ǰABƷĵ۷ֱΪxԪyԪ ?60x?30y?1080?x?16 ? ã? 50x?10y?840y?4?? 50016+45049800 9800-19600.8 9800 𣺴˰ۡ 8. 14. 1920171915֣ ?x?y?4ⷽ飺? 2x?y?5? ˼·1Ԫһη˼·ԪԪһηתΪһԪһη̣дԪͼӼԪ ?x?y?4ٽ⣺1ⷨһ? 2x?y?5?٣ڣ3x9 x3 x3ڣ y1
?x?3ԭĽΪ?
y??1?ⷨ ɢٵ xy4