数推专项答案(华图指导)

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1、(-)等差数列练习1.【答案】Ao解析:逐差后是等比数列。2.【答案】Bo解析:三级等差数列。3.【答案】Bo解析:三级等并数列。4.【答案】Do解析:三级等差数列。5.【答案】Ao解析:三级等并数列。6.【答案】Co解析:三级等并数列。7.【答案】Do解析:逐差后为5,6,11,【答案】Ao解析:逐差后为1,4,27,17,()为和数列。256,(3125)及为11,22,3',4°,55。9.【答案】Co解析:三级差后为-4.5,9,-18为等比数列。10.【答案】A。解析：逐差后为16,-8,4,-2为等比数列。(二)等比数列练习1.【答案】Ao解析:11X1+2=1

2、3,13X2+2=28,28X3+2=86,86X4+2二346。2.【答案】Ao解析:逐差后为3.25,8.5,19,40及3.25X2+2=8-5,8.5X2+2=19,19X2+2=40o3.【答案】Bo解析:1+2X2=5,2+5X2=12,5+12X2=29o4.【答案】Co解析:1+4X2二9,4+9X2二22,9+22X2二53。5.【答案】B。解析:2X1=2,3X2=6,5X6=30,7X30=210,11X210=2310,13X2310二30030。6.【答案】C。解析：(4-1)X4=12,(12-4)X4二32,(32-12)X4二807.【答案】

3、Do解析:2X2-1=3,3X3-2=7,7X4-3=25,25X5-4=121o8.【答案】C。解析:2X8+1=17,17X4+1=69,69X2+1二139。9.【答案】D。解析:65X2+27=157,27X2+11=65,11X2+5=27。10.【答案］Bo解析:11X2+7=29,29X2+7=65,65X2+7=137。(三)和数列练习1.【答案】2.【答案】3.【答案】CoBoDo解析:解析:解析:4.【答案】5.【答案】【答案】【答案】6.7.8.DoAoAoAo解析:解析:解析:解析:1+4-1二4,4+4-1二7,4+7-1二10°(2+1)X3=9

4、,(1+9)X3=30,(9+30)X3二117。题有错误应改为-2,4,0,8,8,24,40,()相邻两项和为2,4,8,16,312,64为等比数列(5-2)X3=9,(9-5)X4二16,(16-9)X5二35。相邻两项和取尾数为下-•项。18+22=40,28+32=60,70+(10)=80。(2+3)X4二20,(3+20)X4二92,(20+92)X4=448o【答案】A。解析：逐差后为2,2,4,8,14,26为和数列，2+2+4=8,2+4+8=14,4+8+14二26。【答案】Ao解析：和数列，一1+0二一1,0+(T)二-1,(一1)+(-1)二一2

5、,(一1)+(-2)二一3。（四）积数列练习1.【答案】D。解析：2X3+1二7,3X7+1=22,7X22+1=155,22X155+1=341lo2.【答案】A。解析：3X7-5=16,7X16-5=107,16X107-5=1707。3.【答案】A。解析：5X3-5=10,3X10-5=25,10X25-3=24704.【答案】Ao解析：相邻两项相乘取尾数为下一项。(五)多次方数列练习1.【答案】D。解析：I等比为3。+1=2,23-1=7,33+1=28,43-1=63,534-1=126o2.【答案】C。解析：1X2=2,2X6=6,3X12=36,4X20=80

6、,5X30=150。3.【答案】B。解析：I1+0=1,213+21+21~55+1=5,33+2=29,4+3=259,55+4=3129o4.【答案】A。解析:03+1=1J3+2=3,23+3=11,33+4=31o5.【答案】D。解析：(5—2)2=9,(9—2)2=49,(49—9)2=1600。6.【答案】C。解析：32+5=14,52-5=20,72+5=54,92-5=76o7.【答案】Bo解析：I2+1=2,22-1=3,33+1=10,42-1=15,52+1=26o8.【答案】B。解析：2"=丄,3」=丄,4一2=丄,5"=丄,6°=17=7。1627

7、1659.【答案】C。解析：1?+2=3,22—2=2,32+2=11,42—2=14,52+2=27,62—2=34。10.【答案】C。解析：0x03=0,1x2?二&2x3?=54,3x4’=192,4x5?=500。（六）分式数列练习1.【答案】B。解析：数列化为6090110125137分子逐差后为30,20,15,12逐商6060606060后为2342【答案山解祝数列化場諾罟分子为和数列。3.【答案】Ao解析:644836274数列化屹亍方分子等比为丁4.【答案】D。解析：9一6二？，6^-=4,-^4