Question

If 7th times the 7th term of an Ap is equal to 11 times its 11th term then its 18th term will be

Answer 1

Secondary SchoolMath 5+3 pts


If 7 times the 7th term of an AP is equal to 11 times the 11th term, show that the 18th term of it is 0
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Report by Chroopa 22.01.2014
Answers

divyak
Divyak Ambitious

7th term = (a+6d) 11th term = (a+10d)
(a+6d)7 since 7th term of the ap is 7 times and the same for 11th term
(a+6d)7=(A+10d)11 (given)
7a + 42d =11a +110d (on solving)
7a - 11a = 110d - 42d
-4a = -68d
a= -17d


we know 18th term = (a+17d)................................. (i)
now we substitute the value of a in (i)
which emplies,
-17d + 17d
= 0
hence proved..

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