Multiple choice

For an A.P. if a25 - a20 = 45, then d equals to:

  1. 9

  2. -9

  3. 18

  4. 23
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

4: (a) 9 [Soln: 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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