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Question 9. The 10th and 18th terms of an A.P. are 41 and 73 respectively. Find 26th term.

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This is arithmetic progression based question from Chapter name- Arithmetic Progression
Chapter number- 9
Exercise – 9.4
In this question we have been given that the 10th and 18th terms of an A.P. are 41 and 73 respectively. Now we have to Find 26th term.

CBSE DHANPAT RAI PUBLICATIONS
Understanding CBSE Mathematics
Class :- 10th
Question no 9

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1 Answer

  1. Solution: 

    Given that,

    A10 = 41 and a18 = 73

    As we know that, to find nth term in an A.P = a + (n – 1)d

    therefore,

    a10 = a + (10 – 1)d

    = a + 9d = 41 ———(i)

    Similarly,

    a18 = a + (18 – 1)d

    = a + 17d = 73 ——-(ii)

    Solving (i) and (ii),

    (ii) – (i)

    a + 17d – (a + 9d) = 73 – 41

    8d = 32

    d = 4

    Using d in (i), we get

    a + 9(4) = 41

    a = 41 – 36 = 5

    Now, the 26th term is given by a26 = 5 + (26 – 1)4 = 5 + 100 = 105

    Hence the 26th term is 105.

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