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 156348: Trying to find the series for my son's "Chicago Math" 7th grade class. It's an exponetial series with the following (x,y) points (1,1), (2,3), (3,6), (4,10), (nth,?).
Help if you can, Thanks!
Click here to see answer by Earlsdon(6294)

Question 157604: The angles of a rectangular triangle are the terms of an arithmetic sequence. Calculate these angles.
Click here to see answer by checkley77(12844)

Question 152401: I need help with my math ASAP!. My teacher sucks at teacher algebra 2!. so if you can place help me that would be great.
Click here to see answer by Alan3354(69443)

Question 157709: The angles of a rectangular triangle are the terms of an arithmetic sequence. Calculate these angles.
Click here to see answer by Alan3354(69443)

Question 154683: Homework Options

A. 45 minutes a day (180 days)
B. 1 second a day, then double the seconds everyday for 30 days. Then no more for the rest of the year.
Which option is better a or b?
180x45=8100 minutes/60=135 hours

i cannot find out how to get option b
Click here to see answer by Alan3354(69443)

Question 158587: im confused on how rto wokr this sequence out
0,14, 52, 126, 248
i have tried n cubed but cannot find the answer?

Click here to see answer by Edwin McCravy(20056)

Question 159126: an arithmetic sequence has t(8)=1056and t(13)=116. What is t(5)
Click here to see answer by Alan3354(69443)

Question 159834: 2m^4 - 2mn^3
Click here to see answer by checkley77(12844)

Question 160195: If Steven can mix 20 drinks in 5 min, Sue can mix 20 drinks in 10 min, and Jack can mix drinks in 15 min. How much time will it take all 3 of them working together to mix the 20 drinks?
The answer is 2 min and 44 seconds, but I don't know how.
Click here to see answer by ankor@dixie-net.com(22740)

Question 161137: rita has two more than three times the number of baseball cards then ben has. if rita gave ben 12 card,they would have the same number of cards. how many cards did rita start with?
Click here to see answer by jojo14344(1513)

Question 161213: solve this problem please...what is the next sequence-- 1,2,6,42,1806,...
Click here to see answer by vleith(2983)

Question 161287: Find the first 10 terms of each sequence:
An=An-1+2xAn-2
A1 = 1 A2 = 5
Click here to see answer by vleith(2983)

Question 161556: Please can you help me with Arithmetic Sequences because I don't know how to do it. The problem say determine whether each sequence is an arithmetic sequence. If it is, state the common difference.
The problem is 10,12,15,18,....
Thanks for your help because I don't get how to do it so if you help me out to were I can do it on my own then thanks a lot.It's on page 236 my teacher wants me to do all the even numbers on the practice and apply.
Click here to see answer by Earlsdon(6294)

Question 161554: Please can you help me with Arithmetic Sequences because I don't know how to do it. The problem say determine whether each sequence is an arithmetic sequence. If it is, state the common difference.
The problem is 17,6,5,4,....
Thanks for your help because I don't get how to do it so if you help me out to were I can do it on my own then thanks a lot.It's on page 236 my teacher wants me to do all the even numbers on the practice and apply.
Click here to see answer by Alan3354(69443)

Question 161612: Please help my 7th grade son figure out how to answer the following:
determine the general term for the following sequence:
1, 2/5, 1/3, 4/13, 5/17, .....
we figured out the differences and got: .6, 0.66, .03, .01 (decreases at a variable rate) please help!!!!!

Click here to see answer by Alan3354(69443)

Question 161818: Please can you help me with Arithmetic Sequences because I don't know how to
do it. The problem say determine whether each sequence is an arithmetic
sequence. If it is, state the common difference.
The problem is -15,-11,-7,-3,....
Thanks for your help because I don't get how to do it so if you help me out to
were I can do it on my own then thanks a lot.It's on page 236 my teacher wants
me to do all the even numbers on the practice and apply.

Click here to see answer by scott8148(6628)

Question 161823: Please can you help me with Arithmetic Sequences because I don't know how to
do it. The problem say determine whether each sequence is an arithmetic
sequence. If it is, state the common difference.
The problem is -31,-22,-13,-4,....
Thanks for your help because I don't get how to do it so if you help me out to
were I can do it on my own then thanks a lot.It's on page 236 my teacher wants
me to do all the even numbers on the practice and apply.
Click here to see answer by checkley77(12844)

Question 161822: Please can you help me with Arithmetic Sequences because I don't know how to
do it. The problem say determine whether each sequence is an arithmetic
sequence. If it is, state the common difference.
The problem is 18,24,30,36,....
Thanks for your help because I don't get how to do it so if you help me out to
were I can do it on my own then thanks a lot.It's on page 236 my teacher wants
me to do all the even numbers on the practice and apply.
Click here to see answer by checkley77(12844)

Question 161819: Please can you help me with Arithmetic Sequences because I don't know how to
do it. The problem say determine whether each sequence is an arithmetic
sequence. If it is, state the common difference.
The problem is 2.1,4.2,8.4,17.6,....
Thanks for your help because I don't get how to do it so if you help me out to
were I can do it on my own then thanks a lot.It's on page 236 my teacher wants
me to do all the even numbers on the practice and apply.

Click here to see answer by checkley77(12844)

Question 161829: Please can you help me with Arithmetic Sequences because I don't know how to
do it. The problem say determine whether each sequence is an arithmetic
sequence. If it is, state the common difference.
The problem is 7/12,1_1/3,2_1/12,2_5/6,....
Thanks for your help because I don't get how to do it so if you help me out to
were I can do it on my own then thanks a lot.It's on page 236 my teacher wants
me to do all the even numbers on the practice and apply.
An arithmetic sequence happens when the difference between successive terms is always the same (i.e. you get the next terms by adding or subtracting the same number to the previous one)
Quick example 1, 7, 13, 19
1+6=7+6=13+6=19....in this case the common difference is 6
Now in your situation you want to see if the numbers in your sequence are increasing by the same number.
1. When dealing with fractions and mixed numbers it is always a good idea to change mixed numbers to improper fractions
2. When dealing with fractions and arithmetic sequences you should first make sure all fraction have the same denominator...
1st term: 7/12
2nd term: 1_1/3=4/3 * (4/4)=16/12
3rd term: 2_1/12=25/12
4th term: 2_5/6=17/6 * (2/2)=34/12
Now find the difference between the 2nd term and 1st term: 16/12 - 7/12 = 9/12
Find the difference between the 3rd term and the 2nd term: 25/12 - 16/12= 9/12
And the difference between the 4th term and 3rd term is also 9/12
Therefore, the sequence is arithmetic and the common difference is 9/12
Click here to see answer by eperette(173)

Question 162259: 5y-7/2+4x-3/6=18-5x
Click here to see answer by elima(1433)

Question 163437: Three solutions to the equation Ax-By-Cz-5=0 are (2,4,-1),(3,6,-2), and(-2,-9,-4). Find C.
Click here to see answer by Edwin McCravy(20056)

Question 164048: i realy need a little help with this:
1+2+3+4+5+6...... find the sum of the 20th term?
Click here to see answer by Alan3354(69443)

Question 164324: how many 1's are between the numbers 1-500 ? I have tried to rite down all the numbers that have the number 1 in them and i came up with 150. Am I rite ? I am in 5th grade and this is for a study guide for a math tournament .
Click here to see answer by Fombitz(32388)

Question 164464: I need help figuring out the next number in this sequence. the problem is... 3;9;81;6;561
Click here to see answer by checkley77(12844)

Question 164633: i have this question t(n)=4n-3 and it says write down the first five terms of the sequence. i do not understand how to find the terms of this sequence.
Click here to see answer by scott8148(6628)

Question 165152: calculate the 12th term using the formula 2-5a
Click here to see answer by Edwin McCravy(20056)

Question 165484: 1,2,4,8,16,32,64,128... Find the 24th term
Click here to see answer by stanbon(75887)

Question 165495: I need a little help!!
Find the sum of the first 20 terms of this series
1 + 8 + 64 + 512 . . . .
I figured out this is a geometric series with a ratio of 8.
The formula I'm using is Sn=t1(1-r^n)/1-r
This is what I have so far S20=1(1-(8)^20)/1-8
Is this right so far? And what do I do with the -7 as a denominator?
Click here to see answer by Alan3354(69443)

Question 165715: mary has 36 bill in her piers, 10 bills and 20 bills in total 460 dollars,
how many 10 and 20 bills are in her piers

Click here to see answer by checkley77(12844)

Question 166043: COMPLETE THE ORDERED PAIRS:
2X+3Y=7
(0, ) (2, ) ( ,3)

Click here to see answer by oscargut(2103)

Question 166155: How to derive Nth term of the following series?
1,3,6,10,15,21.........upto n terms 25!!!!!!!!!!!!!!!!!!!!!!!!!
Click here to see answer by 35qt(1)

Question 166155: How to derive Nth term of the following series?
1,3,6,10,15,21.........upto n terms 25!!!!!!!!!!!!!!!!!!!!!!!!!
Click here to see answer by Fombitz(32388)

Question 166647: you are building an addition on to your house. you only have enough money to buy 70 feet or exterior building materials. one side will be against the original house, so you only have to have materials for 3 sides. what would be the dimensions of the additon needed to give the maximim area? the is the maximum area?

thank you i really need help
Click here to see answer by ankor@dixie-net.com(22740)

Question 166889: Two numbers have a difference of 10 and the sum of 34. What are the numbers?
Click here to see answer by checkley77(12844)

Question 167753: Miku and John began biking from the same place on the same road, heading in the same direction. Each day, Miku bikes 25 miles. John bikes 5 miles the first day, 8 miles the second day and so on. Each day, biking three more miles than he biked the previous day. If they began on July 1, on waht date did John passed Miku?
I got the answer with a table but i dont know how to show it into algebraic equation.
How do you change John's pattern into an equation?
5,13,24,38,56,76,99,125...........
My work so far:
Miku= 25x x = days
John= 5+(5+3)+(5+3+3)+(5+3+3+3).....
5x+???= nth term

so far, the only part of the equation ive figured out is the 5x....
though i think that there should be a disributive property in the equation.
Im really confused and have been working this problem for hours.
I really need help.
Click here to see answer by scott8148(6628)

Question 168611: What is the sum of all multiples of 6 that are strictly between 3128 and 51804?
Click here to see answer by jim_thompson5910(35256)

Question 168807: Cell Division: One leukemic cell injected into a healthy mouse will divide into two cells in about 1/2 day. At the end of the day these two cells will divide again, with the doubling process continuing each 1/2 until there are 1 billion cells, at which time the mouse dies. On which day after the experiment is started does this happen?
I'm having a horrible time coming up with a formula for this problem.
I would appreciate any help you can give me on this one.
Thank you so much, ahead of time!

Click here to see answer by Alan3354(69443)

Question 169218: Have trouble understanding sequences, can anyone give assistance?
Find ratio, r, the general term, a(base-n), and a(base-11)
2,-6,18,-54,162,...
Click here to see answer by Mathtut(3670)

Question 169219: How do I find the next two terms of geometric sequence 6250, 5000, 4000,...
and also how do I find four geometric means between 4096 and 972. I must show my work and don't know how to do these.
Please help.
Thanks
Click here to see answer by checkley77(12844)

Question 169224: I need to find a counterexample to the statement 4^n+1 is divisible by 5. Can someone please show me how to do this.
Thanks
Click here to see answer by Edwin McCravy(20056)

Question 169216: Don't understand sequences, can anyone help?
Evaluate this sum:
S= 15 + 9 + 27/5 + 81/25 +.......
Click here to see answer by Mathtut(3670)

Question 169349: Can someone please help. I am lost on how to start this problem.
Find the sum of the infinite geometric series 36+12+16+...if it exists.
I have to show my work and don't know where to begin.
Thanks.
Click here to see answer by Alan3354(69443)

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