全國(guó)初中數(shù)學(xué)聯(lián)賽試題-資料下載頁
2025-01-14 00:46本頁面
【正文】 ②由于均為自然數(shù)，判斷易知，使得等式②成立的只有兩組：和（1）當(dāng)時(shí)，.又為三角形的三邊長(zhǎng)，所以，即，即，所以可以取值4，5，6，7，8，對(duì)應(yīng)可得到5個(gè)符合條件的三角形.（2）當(dāng)時(shí)，.又為三角形的三邊長(zhǎng)，所以，即，即，所以可以取值2，3，4，5，6，7，對(duì)應(yīng)可得到6個(gè)符合條件的三角形.綜合可知：符合條件且周長(zhǎng)不超過30的三角形的個(gè)數(shù)為5＋6＝11.二．（本題滿分25分）題目和解答與（A）卷第二題相同.三．（本題滿分25分）題目和解答與（A）卷第三題相同.第二試 （C）一．（本題滿分20分）題目和解答與（B）卷第一題相同.二．（本題滿分25分）題目和解答與（A）卷第二題相同.三．（本題滿分25分）設(shè)是大于2的質(zhì)數(shù)，k為正整數(shù)．若函數(shù)的圖象與x軸的兩個(gè)交點(diǎn)的橫坐標(biāo)至少有一個(gè)為整數(shù)，求k的值．解 由題意知，方程的兩根中至少有一個(gè)為整數(shù)．由根與系數(shù)的關(guān)系可得，從而有 ①（1）若，則方程為，它有兩個(gè)整數(shù)根和．（2）若，則.因?yàn)闉檎麛?shù)，如果中至少有一個(gè)為整數(shù)，則都是整數(shù).又因?yàn)闉橘|(zhì)數(shù)，由①式知或．不妨設(shè)，則可設(shè)（其中m為非零整數(shù)），則由①式可得，故，即．又，所以，即 ②如果m為正整數(shù)，則，從而，與②式矛盾.如果m為負(fù)整數(shù)，則，從而，與②式矛盾.因此，時(shí)，方程不可能有整數(shù)根．綜上所述，．standards and specifications, serial number a 1 GB33232005 steel fusion welded butt joints, welding engineeringRay lighting and quality rating of 2 GB1134589 steel welds manual methods of ultrasonic inspection and testing results for grade 3 GB502362002 industrial pipe welding engineering code for construction and acceptance of field equipment 4 HGJ22292 technical specification for welding of aluminium and its alloys 5 low temperature steel welding procedure 6 SH35252004 petrochemical JB/ T47082000 of welding procedure qualification for steel pressure vessels 7 JB/47092000 8 JB47302005 pressure vessel welding procedures of steel pressure vessel NDT 9 JB/T47442000 steel pressure vessel products mechanical properties test of welded plate II, mechanical equipment installation engineering 1 GB15098 2 GB501282005 vertical cylindrical steel pressure vessel steel welded tank code for construction and acceptance of 3 JB/ T47351997 steel welded atmospheric pressure vessel 4 GB502312009 mechanical equipment installation engineering construction and acceptance specification for 5 GB5027598 pressor, fan and pump installation engineering construction and acceptance specification for lifting 6 HG202012000 construction installation engineering construction standard 7, HG ... Pressure gauges, using an installed spark arrestor for acetylene cylinders, illegal carrying, using gas cylinders, each operator fined 20 Yuan. Gas bottle without the hot sun exposure measures, responsibilities of team a fine of 50 Yuan. (7) at height and the opening and provisional protective measures have been taken, the responsible unit fined 200 Yuan, construction person in charge a fine of 50 Yuan. (8) no permit to work and the job in accordance with the provisions, on the job unit fined 300 yuan, the unit will charge
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