Questions on Algebra: Sequences of numbers, series and how to sum them answered by real tutors!

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Question 1005816: Special Sequences help?
1. Find the 4th term if the sequence in which a1 = 2 and an+1 = -4an + 2.
I keep getting -128 as the answer. This is my work.
a1 = 2
a2 = -8 + 2 = -6
a3 = -32 + 2 = - 30
a4 = -120 + 2 = -128

Please help! Thank you so much!

Click here to see answer by jim_thompson5910(35256)

Question 1005865: What is the similarity of between these numbers 85,17,19,4,2
Click here to see answer by rothauserc(4718)

Question 1005949: Write down the first term and the common difference of the arithmetic progression whose
fifth term is 52 and the difference of the 9th and 13th term is 40.
I've tried and come up with this but I'm pretty certain it's wrong
Difference between the 13th and 9th term = (a + 12d) � (a + 8d) = 4d = α
Fifth term is a + 4d = 52
First term a = 52 � α
Common difference d = α/4
Click here to see answer by skitzboy(1)

Question 1005969: What is the function for the sequence 1,4,9,16,25
Click here to see answer by Fombitz(32388)

Question 1005969: What is the function for the sequence 1,4,9,16,25
Click here to see answer by AnlytcPhil(1806)

Question 1005957: if (3-x)+(6)+(7-5x) is a geometric series, find the two possible values for x, the common ratio and the sum of GP
Click here to see answer by josgarithmetic(39617)

Question 1006071: If a, b, c are odd integers, then the equation ax2 + bx + c = 0 has no integer solution.
How can I prove this?
Sorry if its the wrong section >.<
Click here to see answer by ikleyn(52787)

Question 1005952: Write down the first term and the common difference of the arithmetic progression whose
fifth term is 52 and the difference of the 9th and 13th term is 40.
I've tried and come up with this but I'm pretty certain it's wrong
Difference between the 13th and 9th term = (a + 12d) � (a + 8d) = 4d = α
Fifth term is a + 4d = 52
First term a = 52 � α
Common difference d = α/4
Click here to see answer by MathTherapy(10552)

Question 1006100: How can i find a common difference for this arithmetic sequence?
,,
Click here to see answer by Theo(13342)

Question 1006190: For an arithmetic sequence, find t(n) if:
a. t(3)= 6.5 and s(8)=67
b. t(4)= and s(5)=
Sorry, I really don't know where to start!!
Please write explanations if you can!
Click here to see answer by josgarithmetic(39617)

Question 1006021: A pronic number is the product of two consecutive positive integers.
110 is a pronic number as 110 = 11 x 10.
The sum of two pronic numbers is 240.
What is the difference between these two numbers?
Click here to see answer by KMST(5328)

Question 1006222: Prove that the sum s of the first n natural numbers is given by the
equation s = n/2 (n+1)

Click here to see answer by AnlytcPhil(1806)

Question 1006085: Five hundred and twenty two circular cylinders are stacked in rows in
such a way that the number in a row is one less than in the row below.
The bottom row contains 32 cylinders. How many rows are there?
How many cylinders are there in the top row?
Click here to see answer by Theo(13342)

Question 1006280: 1.given that three numbers form an A.P.their sum is 21,and their product is 231.find these numbers.
Click here to see answer by ikleyn(52787)

Question 1006335: Write the first five terms of the sequence an =5n-2
Click here to see answer by ikleyn(52787)

Question 1006353: we are at salala..where are we?
Click here to see answer by ikleyn(52787)

Question 1006353: we are at salala..where are we?
Click here to see answer by Alan3354(69443)

Question 1006645: the sum of the first four terms of an A.P.is 56.the sum of the last four terms is 112.if the first term is 11,find the number of terms.
Click here to see answer by stanbon(75887)

Question 1006819: Find the first 5 terms of the recursive sequence. A1=3 An=2an-1-3
Click here to see answer by jim_thompson5910(35256)

Question 1006888: A) Which term of the geometric series is: 2187, 729, 243, . . . is 1/9?
B) calculate the sum of the first 5 terms?
Click here to see answer by Fombitz(32388)

Question 1006988: What Is The Similarity Between These Numbers;85,17,19,4 And 2?
Click here to see answer by ikleyn(52787)

Question 1006733: The number 2015 can be written as the sum of two or more consecutive
positive integers in seven different ways. Find the total of the
smallest integers from each of the seven ways.
Click here to see answer by Edwin McCravy(20056)

Question 1006281: 1.given that the tenth, fourth and firt terms of an A.P are the three consecutive terms of the G.P.find the common ratio and the sum of the first six terms,taking the first term to be 4.
Click here to see answer by Edwin McCravy(20056)

Question 1007120: The 3rd and 6th terms of a gp are 108 and _32 respectively find the common ratio and the first term
Click here to see answer by Edwin McCravy(20056)

Question 1006118: 8 12 24 46 72 ? what comes in place of question marks?

Click here to see answer by Edwin McCravy(20056)

Question 1007328: Mrs.Lee invests $800 at 6% per annum and $1200 at 7% per annum.What is her total annual interest on these two investments?

Click here to see answer by addingup(3677)

Question 1007314: Please help me solve i dont understand.
Find first 5 susesions of:
1. an=2(1/3) exponent n-2
2.
5
∑ 2n-5
n-1
Click here to see answer by ikleyn(52787)

Question 1007436: what is the similarity with numbers85,17,19,4 and2

Click here to see answer by Edwin McCravy(20056)

Question 1007603: Sum of one-sixth of x and 2.8

Click here to see answer by Alan3354(69443)

Question 1007664: what the missing terms of 23,25,27,_,_33
Click here to see answer by fractalier(6550)

Question 1007600: Please help I have an idea but dont understad. Thanks
1. Find first 5 susesions of:
an=2(1/3) (fraccion) exponent n-1
2.
250
∑ 4 = (4) + (-4) + 1 + 4 + 4 =
n=1
3.
∑5 (4/5) Exponent n
n=1
Click here to see answer by Theo(13342)

Question 1007796: find the number of terms and the sum of each of the following arithmetic series.
5+7+9+...+11

Click here to see answer by fractalier(6550)

Question 1007831: I need help trying to figure out what the partial sum of the first eight terms for the series 8+16+32+....
Click here to see answer by ikleyn(52787)

Question 1007833: a sum of sh 100000 is to be used to four prizes. If each price is Shs. 10000 less that the previous one. Find the value of each prize
Click here to see answer by ikleyn(52787)

Question 1007852: Find the indicated term of the sequence.
a7 of 9, 45, 225, 1125 . . .

Click here to see answer by fractalier(6550)

Question 1007853: find three consecutive term of a G.P whose sum is 21 and whose product is 64
Click here to see answer by fractalier(6550)

Question 1007842: A man starts saving on 1st November, he save Shs 1 the first day,Shs.2 on second day Shs.4 the third day and so on doubling the amount everyday. If he managed to keep on saving until the end of month, how much would he saved?
Click here to see answer by fractalier(6550)

Question 1007075:
Click here to see answer by fractalier(6550)

Question 1008007: The 2nd term of an A.P is (a-b) and 4th term is (a+b), find the 5th term and sum of the first 5 terms of the A.P
Click here to see answer by josgarithmetic(39617)

Question 1008207: Solve ( 1-1 / 3 ) ( 1-1 / 4 ) ( 1-1 / 5 )-----(1-1 / n )
Click here to see answer by ikleyn(52787)

Question 1008316: Please solve:
Sn=a^2+(a+d)^2+(a+2d)^2+(a+3d)^2+....+[(a+(n-1)d]^2
Sn=a�+(a+d)�+(a+2d)�+(a+3d)�+....+[(a+(n-1)d]�
Click here to see answer by ikleyn(52787)

Question 1008318: Please solve p:
p^2=a^2+(a+d)^2+(a+2d)^2+(a+3d)^2+....+[a+(n-1)d]^2
for n=9, p=?
Click here to see answer by ikleyn(52787)

Question 1008361: A finite arithmetic sequence has 7 terms, and the first term is 3/4. What is the difference between the mean and the median of these 7 terms?
Click here to see answer by ikleyn(52787)

Question 1008716: The sum of three consecutive integers is -27 what are the numbers?
Click here to see answer by Fombitz(32388)

Older solutions: 1..45, 46..90, 91..135, 136..180, 181..225, 226..270, 271..315, 316..360, 361..405, 406..450, 451..495, 496..540, 541..585, 586..630, 631..675, 676..720, 721..765, 766..810, 811..855, 856..900, 901..945, 946..990, 991..1035, 1036..1080, 1081..1125, 1126..1170, 1171..1215, 1216..1260, 1261..1305, 1306..1350, 1351..1395, 1396..1440, 1441..1485, 1486..1530, 1531..1575, 1576..1620, 1621..1665, 1666..1710, 1711..1755, 1756..1800, 1801..1845, 1846..1890, 1891..1935, 1936..1980, 1981..2025, 2026..2070, 2071..2115, 2116..2160, 2161..2205, 2206..2250, 2251..2295, 2296..2340, 2341..2385, 2386..2430, 2431..2475, 2476..2520, 2521..2565, 2566..2610, 2611..2655, 2656..2700, 2701..2745, 2746..2790, 2791..2835, 2836..2880, 2881..2925, 2926..2970, 2971..3015, 3016..3060, 3061..3105, 3106..3150, 3151..3195, 3196..3240, 3241..3285, 3286..3330, 3331..3375, 3376..3420, 3421..3465, 3466..3510, 3511..3555, 3556..3600, 3601..3645, 3646..3690, 3691..3735, 3736..3780, 3781..3825, 3826..3870, 3871..3915, 3916..3960, 3961..4005, 4006..4050, 4051..4095, 4096..4140, 4141..4185, 4186..4230, 4231..4275, 4276..4320, 4321..4365, 4366..4410, 4411..4455, 4456..4500, 4501..4545, 4546..4590, 4591..4635, 4636..4680, 4681..4725, 4726..4770, 4771..4815, 4816..4860, 4861..4905, 4906..4950, 4951..4995, 4996..5040, 5041..5085, 5086..5130, 5131..5175, 5176..5220, 5221..5265, 5266..5310, 5311..5355, 5356..5400, 5401..5445, 5446..5490, 5491..5535, 5536..5580, 5581..5625, 5626..5670, 5671..5715, 5716..5760, 5761..5805, 5806..5850, 5851..5895, 5896..5940, 5941..5985, 5986..6030, 6031..6075, 6076..6120, 6121..6165, 6166..6210, 6211..6255, 6256..6300, 6301..6345, 6346..6390, 6391..6435, 6436..6480, 6481..6525, 6526..6570, 6571..6615, 6616..6660, 6661..6705, 6706..6750, 6751..6795, 6796..6840, 6841..6885, 6886..6930, 6931..6975, 6976..7020, 7021..7065, 7066..7110, 7111..7155, 7156..7200, 7201..7245, 7246..7290, 7291..7335, 7336..7380, 7381..7425, 7426..7470, 7471..7515, 7516..7560, 7561..7605, 7606..7650, 7651..7695, 7696..7740, 7741..7785, 7786..7830, 7831..7875, 7876..7920, 7921..7965, 7966..8010, 8011..8055, 8056..8100, 8101..8145, 8146..8190, 8191..8235, 8236..8280, 8281..8325, 8326..8370, 8371..8415, 8416..8460, 8461..8505, 8506..8550, 8551..8595, 8596..8640, 8641..8685, 8686..8730, 8731..8775, 8776..8820, 8821..8865, 8866..8910, 8911..8955, 8956..9000, 9001..9045, 9046..9090, 9091..9135, 9136..9180, 9181..9225, 9226..9270, 9271..9315, 9316..9360, 9361..9405, 9406..9450, 9451..9495, 9496..9540, 9541..9585, 9586..9630, 9631..9675, 9676..9720, 9721..9765, 9766..9810, 9811..9855, 9856..9900, 9901..9945, 9946..9990, 9991..10035, 10036..10080, 10081..10125, 10126..10170, 10171..10215, 10216..10260, 10261..10305, 10306..10350, 10351..10395, 10396..10440, 10441..10485, 10486..10530, 10531..10575, 10576..10620, 10621..10665, 10666..10710, 10711..10755, 10756..10800, 10801..10845, 10846..10890, 10891..10935, 10936..10980, 10981..11025, 11026..11070, 11071..11115, 11116..11160, 11161..11205, 11206..11250, 11251..11295, 11296..11340, 11341..11385, 11386..11430, 11431..11475, 11476..11520, 11521..11565, 11566..11610, 11611..11655, 11656..11700, 11701..11745, 11746..11790