# If 7 times the 7th term of an A.P. is equal to 11 times the 11th term.Find 18th term of A.P.?

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by dinesh204

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by dinesh204

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(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 prove..