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**ganesh****Administrator**- Registered: 2005-06-28
- Posts: 30,587

Hi,

SP#605. A sum of $700 is to be used to give seven cash prizes to students of a school for their overall academic performance. If each prize is $20 less than its preceding prize, find the value of each of the prizes.

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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**ganesh****Administrator**- Registered: 2005-06-28
- Posts: 30,587

Hi,

SP#606. Show that

form an Arithmetic Progression where is defined as . Also, find the sum of the first 15 terms.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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**666 bro****Member**- From: Flatland
- Registered: 2019-04-26
- Posts: 244

a1, a2, a3 forms an A.P with d=4.

They are:

a1=7

a2= 11

a3=15

S15= 525.

"An equation for me has no meaning, unless it expresses a thought of God"- Srinivasa ramanujan

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**ganesh****Administrator**- Registered: 2005-06-28
- Posts: 30,587

Hi 666 bro,

Neat work!

SP # 607. Show that

form an Arithmetic Progression where is defined as Also, find the sum of the first 15 terms.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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**ganesh****Administrator**- Registered: 2005-06-28
- Posts: 30,587

Hi,

SP # 608. The sum of 15 terms of an Arithmetic Progression with common difference 6 is 780. Write the algebraic expression of the sequence.

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

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**ganesh****Administrator**- Registered: 2005-06-28
- Posts: 30,587

Hi,

SP # 609. Write the algebraic expression for the sum of the sequence.

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

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**666 bro****Member**- From: Flatland
- Registered: 2019-04-26
- Posts: 244

Sp#609: 2sₙ -n(2a+(n-1)d) =0

"An equation for me has no meaning, unless it expresses a thought of God"- Srinivasa ramanujan

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**ganesh****Administrator**- Registered: 2005-06-28
- Posts: 30,587

SP # 610. Write arithmetic sequences with 100 as the sum of the first four terms.

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

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**666 bro****Member**- From: Flatland
- Registered: 2019-04-26
- Posts: 244

Sp#610 the sequences are:

(1) : 10, 20, 30 , 40 where

a = 10 & d = 10.

(2) :25, 25, 25,25 where

a = 25 & d = 0.

"An equation for me has no meaning, unless it expresses a thought of God"- Srinivasa ramanujan

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**ganesh****Administrator**- Registered: 2005-06-28
- Posts: 30,587

Partially correct. Good attempt!

SP# 611. Consider an arithmetic sequence

.(a) Find the algebraic expression of the sequence.

(b) Is there any counting number in the sequence?

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

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**666 bro****Member**- From: Flatland
- Registered: 2019-04-26
- Posts: 244

SP#611 (a) : sₙ = ( n^2) + (10/7)n.

(b) : no,

*Last edited by 666 bro (2020-06-27 20:34:46)*

"An equation for me has no meaning, unless it expresses a thought of God"- Srinivasa ramanujan

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**ganesh****Administrator**- Registered: 2005-06-28
- Posts: 30,587

SP # 612. (a) What is the sum of first 20 natural numbers?

(b) The algebraic form of an arithmetic sequence is 6n + 5. Find the sum of the first 20 terms of this sequence.

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

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**666 bro****Member**- From: Flatland
- Registered: 2019-04-26
- Posts: 244

(a) : s₂₀ = 210.

(b) : s₂₀ = 1360.

"An equation for me has no meaning, unless it expresses a thought of God"- Srinivasa ramanujan

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**ganesh****Administrator**- Registered: 2005-06-28
- Posts: 30,587

Well done!

SP # 613. Sum of first n terms of an arithmetic sequence is 3n² + n. Find the first term and common difference of this sequence.

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

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**666 bro****Member**- From: Flatland
- Registered: 2019-04-26
- Posts: 244

Sp#613: a= 4 & d=6.

"An equation for me has no meaning, unless it expresses a thought of God"- Srinivasa ramanujan

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**ganesh****Administrator**- Registered: 2005-06-28
- Posts: 30,587

Good work!

SP # 614. (a) The fifth term of an arithmetic sequence is 40 and 10th term is 20. What is the 15th term?

(b) How many terms of this sequence make the sum zero?

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

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