For an A.P. if a25 - a20 = 45, then d equals to:
A. 9
B. -9
C. 18
D. 23
Answer: Option A
Solution(By Examveda Team)
an = a + (n - 1) × d⇒ a25 = a + 24d
and a20 = a + 19d
a25 - a20 = 45
⇒ a + 24d - a - 19d = 45
⇒ 5d = 45
⇒ d = 9
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Find the first term of an AP whose 8th and 12th terms are respectively 39 and 59.
A. 5
B. 6
C. 4
D. 3
E. 7
The sum of the first 16 terms of an AP whose first term and third term are 5 and 15 respectively is
A. 600
B. 765
C. 640
D. 680
E. 690
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