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

Tutors Answer Your Questions about Sequences-and-series (FREE)

Question 508190: Im having problems with recursive sequences (An= 3an-1), my secuence is 5,15,45,135... and im trying to make sure how to get 15 with these formula
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Question 508093: given the 5 th term, what is the 50 th term?
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Question 508404: Prove that the sequence 1/ sqrt ( n ) tends to zero.
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Question 508360: if 12th and 25th term of an airthmetic progression are 40 and 131 .then what is the 50th term

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Question 506885: consider an arithmetc sequence whose fourth entry is 2 and whose seventh entry is 4. find the first and second entries of the sequence.
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Question 509295: write the recursive formula for sequence whose first three terms are 1,1, and 3?
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Question 510283: a local toy store sells whistles in packages of 10,20, or 40. if you need 100 whistles for a party, in how many different combinations can you buy them?
Click here to see answer by Edwin McCravy(20056)

Question 511867: Can you aolve this equation, and give me the steps, -3(z+5)=15
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Question 512217: The sum of 6 terms of an arithmetic series is 45, the sum of 12 terms is -18. Find the first term and the common difference.
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Question 512458: This is all the information I was given and I've been trying to figure it out for hours.
The slope of the line is -2/3, but the numbering on the x axis is missing, How many units should each tick mark on the x axis represent?

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Question 512608: 5,5,6,8,11,15 what is the 20th term and 21th
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Question 513048: whats a number whose product with 6 is the same as its sum with 60.
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Question 513048: whats a number whose product with 6 is the same as its sum with 60.
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Question 512989: Evaluate :
1+ (1+2) +(1+2+3) + (1+2+3+4) +............(1+2+.....100)
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Question 513042: If Y = 1/X , write down the value of Y, correct to 2 decimal places, when X = 8
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Question 513337: what is the number pattern 8,16,4,8,2need answer for the next two numbers thanks
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Question 513638: how to solve 3(2a-1)+5=14
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Question 514512: find the 7th term of a sequence when rule is 2+2
find 4th rule when rule is n2-2
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Question 514575: Six times a number equals the sum of that number and negative 20. What is the number?
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Question 514917: Could someone help to solve this question:
Dad wanted his car to be clean and shiny every day for a week to impress a customer of his. To hose and wipe down the car, he offered to pay his son James 15 cents the first day and double the daily payment each succeeding day thereafter. If James accepted the deal, how much money did he make?

$9.60 $12.40 $14.40 $16.20 $19.05 $38.25
Thank you for your help.
Click here to see answer by Maths68(1474)

Question 514934: The 17th term of an arithmetic progression is 81 and the 33th term is 145. Find a and d
a=first term
d=common difference
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Question 515319: How do I find all numbers for which the rational expression is undefined? For this rational expression -(18)/(11y). Please help I am confused!
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Question 515703: I am a fraction whose product with seven is the same as my sum with seven.Who am I?
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Question 516344: Use the Method of Finite Differences to find a function for the following sequences. Explain your process.
a. 9, 5, -5, -21, . . .
b. 2.5, 6, 13.5, 25, . . .
Ok...This is what I have done.
For "a" there is a second common difference of -6, and for "b" there is a second common difference of 4. Now I have forgotten how to use the method of finite differences. I remember learning something about generating the sequence by using:
a_n+1 = a_n + (the second common difference)n + something?
But I�m not sure this is what I need to use�I�m sure if I could just see �a� done I can do �b�. Thanks in advance for the help!

Click here to see answer by stanbon(75887)

Question 516669: algebraic expression for the Nth term 2, 4, 8, 16, 32, 64,
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Question 517096: what is the nth term for
10,17,24,31,38,
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Question 517313: 45 is 54% of what?
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Question 517315: 45 is 54% of what?
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Question 517484: Trying to understand this number pattern; Can you give me input? Thank you!
X Y
0 0
1 1
2 8
3 27
4 64
5 ___
6 ___
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Question 519025: Find the odd one out
217, 343, 154, 231, 168, 294
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Question 519025: Find the odd one out
217, 343, 154, 231, 168, 294
Click here to see answer by solver91311(24713)

Question 519028: Which number comes next in this series? 1/64, 1/32, 1/16, 1/8, 1/4, 1/2, ?
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Question 519541: One number is 12 less than another number. Their product is -32. What is the least value the smaller number could be?
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Question 520369: OK. I have 6(t+w)to the second +11(t+w)-10
The book gives me this answer (3t+3w-2)(2t+2w+5)I can see where the numbers are from the original equation but I don't see how to get there. How would you determine that you would not use a (nx+b)(nx-c) format and you would have to use 3 numbers in each set?
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Question 520438: What is the sum of 1 1/4 + 0.8?
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Question 520848: The first term of an A.P is 7 and the sum of the first 40 terms is 1216. Find the nth term, and the 20th term.
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Question 521102: the ratio of men to women is 3 to 4 and the ratio of americans to non americans is 7 to 2 if the number of people in the room is less than 100, how many people are in the room?
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Question 521167: expand: (x+3)^12
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Question 521172: expand:(x^2+y^2)^13
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Question 521188: hi i was wondering what the numerical pattern is for 7,19,31,43
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Question 521188: hi i was wondering what the numerical pattern is for 7,19,31,43
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Question 522593: please help me solve this challenge question on arithmetic sequences: if the 9th term of an arithmetic sequence is 27 and the 25th term is 123 what is the first term of the sequence
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Question 522654: how many numbers between 150 and 300 are divisible by 7?
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Question 523201: if every fourth trick-or-treater is a vampire, and every 6th, robot, how many of each will you see if seventy-five trick -or treaters come to your door?
Click here to see answer by stanbon(75887)

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