Sequence And Series Question 346
Question: If twice the 11th term of an A.P. is equal to 7 times of its 21st term, then its 25th term is equal to
[J & K 2005]
Options:
A) 24
B) 120
C) 0
D) None of these
Show Answer
Answer:
Correct Answer: C
Solution:
Let the first term of A.P. is a and common difference is d. 11th term of A.P. = $ a+10d $ 21st term of A.P. = a+ 20d $ 2(a+10d)=7(a+20d) $ Þ $ 2a+20d=7a+140d $ $ 5a+120d=0 $ Þ $ a+24d=0 $ Hence 25th term is 0.
BETA
