SOLUTION: If 7 times the 7th term of an Ap is equal to 11 times its 11th term 'show that its 18th term is 0

Question 1085431: If 7 times the 7th term of an Ap is equal to 11 times its 11th term 'show that its 18th term is 0
Answer by ikleyn(52788) (Show Source): You can put this solution on YOUR website!
.

We are given

 = .   ---->

 =   ---->

 +  = 0  ---->

 +  = 0  --->  (cancel the factor 4 in both sides)  ---->

 = 0  --->

 = 0.

QED.

Solved.

There is a bunch of lessons on arithmetic progressions in this site:
    - Arithmetic progressions
    - The proofs of the formulas for arithmetic progressions
    - Problems on arithmetic progressions
    - Word problems on arithmetic progressions
    - Mathematical induction and arithmetic progressions
    - One characteristic property of arithmetic progressions
    - Solved problems on arithmetic progressions

Also, you have this free of charge online textbook in ALGEBRA-II in this site
    - ALGEBRA-II - YOUR ONLINE TEXTBOOK.

The referred lessons are the part of this online textbook under the topic "Arithmetic progressions".

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