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 307187: The cardinal number of the set {cow, horse, goat, chicken, rooster} is _________.
Thank you
Click here to see answer by richwmiller(17219)

Question 307187: The cardinal number of the set {cow, horse, goat, chicken, rooster} is _________.
Thank you
Click here to see answer by nyc_function(2741)

Question 307188: what is the number of subsets of set B = {12, 14, 16, 18, 20, 22, 24}?
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Click here to see answer by jim_thompson5910(35256)

Question 307087: What is the formula for the following sequence:
12, 42, 92, 162,...
Click here to see answer by richwmiller(17219)

Question 307189: The National Association for Women in Science asked recent high school grads if they had taken certain science classes. Of those surveyed, 75 said they had taken physics, 121 said they had taken chemistry and 11 said they had taken both. Fifteen said they had taken neither. How many recent high school grads were surveyed?
Thank you

Click here to see answer by dabanfield(803)

Question 307192: Given these sets:
A = {3, 4, 5, 6, 7}
B = {6, 7, 8, 9}
C = {2, 4, 6, 8}

List the elements of this set
C ∩ (AB)
Please show steps ,Thank you
Click here to see answer by jim_thompson5910(35256)

Question 307192: Given these sets:
A = {3, 4, 5, 6, 7}
B = {6, 7, 8, 9}
C = {2, 4, 6, 8}

List the elements of this set
C ∩ (AB)
Please show steps ,Thank you
Click here to see answer by dabanfield(803)

Question 307267: In mathematics, n! means the product of the numbers from 1 to n.
For example, 3! = 1 � 2 � 3. Determine the one�s digit of the sum
1! + 2! + 3! + � � � + 18! + 19! + 20!
a 0 b 3 c 5 d 7 e 9
Click here to see answer by Theo(13342)

Question 307271: hey, can you point me in the right direction for writing an equation for the geometric sequence -10, 5, -5/2......
i know a_1 = -10 , and r= -1/2
Click here to see answer by Theo(13342)

Question 307358: I need to complete the pattern...HELP!!! Thanks so much for your help!
x.....y
1.....0
2.....2
4.....12
5......20
10....90
___....380
___....870
___....30
___....42
y = ______
Click here to see answer by vksarvepalli(154)

Question 307937: what is the next number in the following series 12, 12, 18, 36, 90, 270 ?
Click here to see answer by TX911(36)

Question 307890: 2, -4, 8, ....
The first term of the sequence above is 2, and every term after the first term is -2 times the preceding term. How many of the first 50 terms of this sequence are less than 100?
Click here to see answer by scott8148(6628)

Question 308340: A data set has a z-score of 3 for the value 32 and a mean of 20. Find the standard deviation.

I don't understand how to solve it. Instead of just giving the answer, could you explain? Thank you. :-)
Click here to see answer by Fombitz(32388)

Question 308381: The sum of and is?
Click here to see answer by ichudov(507)

Question 308395: 9,19,40,......146? what is the solution for this?
Click here to see answer by Fombitz(32388)

Question 308365: I have a question. I have been given to find the 15th term, when I know the 3rd term to be 7 and 20th term to 43. I trying to figure the common difference and the what the 15th term is.
Click here to see answer by Fombitz(32388)

Question 308438: WHY DIDNT THEY ANSWER MY MATH PROBLEM

Click here to see answer by JBarnum(2146)

Question 308437: {2x+y=5 {4x+2y=6

Click here to see answer by checkley77(12844)

Question 308542: what is the 10th # in this sequence 1,2,4: there are 5 possible answers please help
Click here to see answer by Alan3354(69443)

Question 308542: what is the 10th # in this sequence 1,2,4: there are 5 possible answers please help
Click here to see answer by scott8148(6628)

Question 308592: Please answer the below series and clarify the calculation.
13 57 911 1315 1719
Click here to see answer by vksarvepalli(154)

Question 309008: Is the formula explicit or recursive? Find the first five terms of the sequence.
a. recursive; 1, -4, 16, -64, 256
b. recursive; 0, -16, -24, -48, -80
c. explicit; 1, -4, 16, -64, 256
d. explicit; 0, -8, -24, -48, -80
Click here to see answer by jim_thompson5910(35256)

Question 309107: Evaluate the series 1+2+4+8... to
a. 256.5
b. 511
c. 1023
d. 2047
Click here to see answer by ichudov(507)

Question 309124: Can you help me with this? I am lost as to how to determine the a(1) before I solve. Thank you in advance.
Find the sum of the arithmetic sequence having the data given.
a(n)=5, d=-2, n=12
Tina

Click here to see answer by Fombitz(32388)

Question 309315: Given the sequence 20, 24, 28, 32, 36, . . . find the 60th term.
a. 216 b. 64 c. 256 d. 60 e. 80
Click here to see answer by stanbon(75887)

Question 309333: find the 31st term of the aritmctic sequence 23,36,49,.....
Click here to see answer by stanbon(75887)

Question 309332: find the sum of the arithmetic series.-4,+1+6+11+........+91
Click here to see answer by stanbon(75887)

Question 309331: fi8nd the sum of the arithmetic series.-4,+1+6+11+........+91
Click here to see answer by Fombitz(32388)

Question 309515: Find the first five terms of the sequences with the nth term given as follows:
5n + 5, __, __, __, __, __

Click here to see answer by alicealc(293)

Question 310073: Use differences to find a pattern in the sequence.
-2, -5, -7, -7, -4, 3, 15,
What is the next term?
Click here to see answer by checkley77(12844)

Question 310266: Please help me solve this...
write the following in summation notation
1+6+13+22...
Click here to see answer by Edwin McCravy(20056)

Question 310517: You have a series of numbers, where the sum of the previous two numbers (except for the first two) adds up to the next one. (Like the Fibanachi sequence), the first number is 1 and the 10th number is 111. What is the second number?
Click here to see answer by Edwin McCravy(20056)

Question 310633: I can't remember how to solve the infinite series.
1. What is the solution to the infinite geometric series... the lower limit is = to 1. The upper limit is the infinite symbol. 0.8(0.2)^(n-1).
Now I know the formula is a1/1 - r. But I can't remember which goes for A1 and which goes for r.
2. What is the solution to the infinite geometric series... the lower limit is = to 1. The upper limit is the infinite symbol. (-2/3)^(n-1)
Click here to see answer by stanbon(75887)

Question 310163: How do I solve the sum of the first two terms of an arithmetic sequence is 16. The sum of the second and third term is 28. Determine the first three terms, algebraically.
Click here to see answer by Lament(1)

Question 310934: 0+1+2+3+4+5+6+7+8+9 what is the sigma notation for the series?

Click here to see answer by Edwin McCravy(20056)

Question 310934: 0+1+2+3+4+5+6+7+8+9 what is the sigma notation for the series?

Click here to see answer by palanisamy(496)

Question 310933: 0+1+2+3+4+5+6+7+8+9 what is the sigma notation for the series?
Click here to see answer by Edwin McCravy(20056)

Question 312331: please help me write the series in summation notation.
3+12+21+30+39+48+57
and
125+50+20+8+....
Click here to see answer by solver91311(24713)

Question 312694: The first difference of a sequence is 6, 10,14,18. The sum of the first two terms of the original sequence is 24. Find the first three term of the original sequence. the first term of the original sequence is?
Click here to see answer by Fombitz(32388)

Question 313209: average for 100% + 100% + 45% + 84% + 62% + 91%=?

Click here to see answer by stanbon(75887)

Question 313437: find a number whose product with 6 is the same as its sum with 60. show all steps or reasoning. be sure to check your answer for reasonableness.
Click here to see answer by rfer(16322)

Question 314137: What is the sum of the series
1^2 � 2^2 � 3^2 + 4^2 + 5^2 � 6^2 � 7^2 + 8^2 + � + 24^2?
Click here to see answer by Fombitz(32388)

Question 314406: fimd the sum of the first 30 numbers:6+10+14+18+22
Click here to see answer by Jstrasner(112)

Question 314509: The next number in the sequence 4, 5, 8, 13, 20, 29, ... is :
Click here to see answer by Fombitz(32388)

Question 314463: the sum of the first n terms,Sn of a series is given by Sn=2n*2/(n*n)+1,then
is the third term is 9/5?
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