# Math Is Fun Forum

Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫  π  -¹ ² ³ °

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## #1101 2021-01-02 06:13:14

irspow
Member
Registered: 2005-11-24
Posts: 1,055

### Re: Series and Progressions

I am at an age where I have forgotten more than I remember, but I still pretend to know it all.

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## #1102 2021-01-02 13:10:08

ganesh
Registered: 2005-06-28
Posts: 33,015

### Re: Series and Progressions

Hi,

SP#623. The common difference between 12th and 8th term of an arithmetic sequence is 20. Find the common differene.

It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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## #1103 2021-01-20 06:20:05

irspow
Member
Registered: 2005-11-24
Posts: 1,055

### Re: Series and Progressions

I am at an age where I have forgotten more than I remember, but I still pretend to know it all.

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## #1104 2021-01-20 15:12:57

ganesh
Registered: 2005-06-28
Posts: 33,015

### Re: Series and Progressions

Hi,

Well done!

SP#624.  Write the algebra of 17, 20, 23, .... Is 400 a term of this sequence?

It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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## #1105 2021-01-21 05:19:55

irspow
Member
Registered: 2005-11-24
Posts: 1,055

### Re: Series and Progressions

I am at an age where I have forgotten more than I remember, but I still pretend to know it all.

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## #1106 2021-01-21 15:37:42

ganesh
Registered: 2005-06-28
Posts: 33,015

### Re: Series and Progressions

Hi,

Neat work!

SP#625. Write the algebra of the sum of the sequence 6n + 5. Can the sum 2000? Why?

It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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## #1107 2021-01-22 05:59:40

irspow
Member
Registered: 2005-11-24
Posts: 1,055

### Re: Series and Progressions

I am at an age where I have forgotten more than I remember, but I still pretend to know it all.

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## #1108 2021-01-22 14:22:07

ganesh
Registered: 2005-06-28
Posts: 33,015

### Re: Series and Progressions

Hi,

Brilliant!

SP#625. Let the algebraic expression of an arithmetic sequence be 6n + 3.
i) Find the sum of the first 20 terms of the sequence.
ii) Write the algebraic expression of the sum.

It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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## #1109 2021-01-23 05:41:12

irspow
Member
Registered: 2005-11-24
Posts: 1,055

### Re: Series and Progressions

I am at an age where I have forgotten more than I remember, but I still pretend to know it all.

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## #1110 2021-01-23 15:04:55

ganesh
Registered: 2005-06-28
Posts: 33,015

### Re: Series and Progressions

Hi,

Neat work!

SP#626. Consider an arithmetic sequence whose sum of first 9 terms is 261 and sum of next 6 terms is 444. Find the first term and common difference.

It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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## #1111 2021-01-24 06:03:48

irspow
Member
Registered: 2005-11-24
Posts: 1,055

### Re: Series and Progressions

I am at an age where I have forgotten more than I remember, but I still pretend to know it all.

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## #1112 2021-01-24 14:56:10

ganesh
Registered: 2005-06-28
Posts: 33,015

### Re: Series and Progressions

Hi,

Neat work!

SP#627.  Consider an arithmetic sequence whose sum of first 9 terms is 261 and sum of next 6 terms is 444.
(a) Write the algebraic expression of the sequence.
(b) Wtite the algebraic expression of the sum of the sequence.

It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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## #1113 2021-01-25 05:57:59

irspow
Member
Registered: 2005-11-24
Posts: 1,055

### Re: Series and Progressions

I am at an age where I have forgotten more than I remember, but I still pretend to know it all.

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## #1114 2021-01-25 15:14:08

ganesh
Registered: 2005-06-28
Posts: 33,015

### Re: Series and Progressions

Hi,

Excellent! Both parts are correct!

SP#628. Write the algebraic form of the arithmetic sequence 1, 4, 7, 10, ....
(b) Is 100 a term of the sequence?

It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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## #1115 2021-01-26 03:19:35

irspow
Member
Registered: 2005-11-24
Posts: 1,055

### Re: Series and Progressions

Last edited by irspow (2021-01-27 05:14:48)

I am at an age where I have forgotten more than I remember, but I still pretend to know it all.

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## #1116 2021-01-26 16:05:37

ganesh
Registered: 2005-06-28
Posts: 33,015

### Re: Series and Progressions

Hi,

First part is correct, the second part is not. I think it is be oversight! Neat work for the first part!

SP#629. Consider an arithmetic sequence whose common difference is 7 and sum of first 20 terms is 1530. Write the algevraic expression of the sequence.

It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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## #1117 2021-01-27 05:38:43

irspow
Member
Registered: 2005-11-24
Posts: 1,055

### Re: Series and Progressions

Whoops I subtracted two from 100 instead of adding two. 100 was the 34th term of the sequence. Details matter

Last edited by irspow (2021-01-27 05:39:14)

I am at an age where I have forgotten more than I remember, but I still pretend to know it all.

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## #1118 2021-01-27 15:16:35

ganesh
Registered: 2005-06-28
Posts: 33,015

### Re: Series and Progressions

Hi,

Neat work!

SP#630. If ten times tenth term of an arithmetic sequence is equal to fifteen times fifteenth term, find the twenty-fifth term.

It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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## #1119 2021-01-28 09:58:55

irspow
Member
Registered: 2005-11-24
Posts: 1,055

### Re: Series and Progressions

I am at an age where I have forgotten more than I remember, but I still pretend to know it all.

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## #1120 2021-01-28 14:53:35

ganesh
Registered: 2005-06-28
Posts: 33,015

### Re: Series and Progressions

Hi,

Good work!

SP#631. Find the sum of n terms of the sequence 6, 10, 14, ....
(b) How many terms of the sequence from the beginning in an order makes the sum 240?
(c) Can the sum of the first few terms in an order to make the sum 250?

It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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## #1121 2021-01-29 06:27:26

irspow
Member
Registered: 2005-11-24
Posts: 1,055

### Re: Series and Progressions

I am at an age where I have forgotten more than I remember, but I still pretend to know it all.

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## #1122 2021-01-29 15:27:15

ganesh
Registered: 2005-06-28
Posts: 33,015

### Re: Series and Progressions

Hi,

Excellent!

SP#632. Can the difference between any two terms of an arithmetic sequence having common difference 6 be 2016? Justify tour answer.

It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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## #1123 2021-01-30 05:14:24

irspow
Member
Registered: 2005-11-24
Posts: 1,055

### Re: Series and Progressions

I am at an age where I have forgotten more than I remember, but I still pretend to know it all.

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## #1124 2021-01-30 15:07:55

ganesh
Registered: 2005-06-28
Posts: 33,015

### Re: Series and Progressions

Hi,

Neat work!

SP#633. Two terms of an arithmetic sequence having natural number terms are 50 and 85. Also, 60 is not a term of this sequence. Is 134 a term of this sequence? Justify your opinion.

It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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## #1125 2021-01-31 06:38:13

irspow
Member
Registered: 2005-11-24
Posts: 1,055

### Re: Series and Progressions

I am at an age where I have forgotten more than I remember, but I still pretend to know it all.

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