Adv
Deepak Bora
  • 0

Choose the correct choice in the following and justify. (i) 30th term of the A.P: 10,7, 4, …, is (A) 97 (B) 77 (C) −77 (D) −87

  • 0

This question is from NCERT Book class 10th Ch. no.5 Ex. 5.2 Q. 1 . In this question you have to find the right option and support your answer by giving its solution. Answer the question with brief explanation.

Share

Related Questions

1 Answer

  1. (i) Given here,

    A.P. = 10, 7, 4, …

    Therefore, we can find,

    First term, a = 10

    Common difference, d = a2 − a= 7−10 = −3

    As we know, for an A.P.,

    an = a +(n−1)d

    Putting the values;

    a30 = 10+(30−1)(−3)

    a30 = 10+(29)(−3)

    a30 = 10−87 = −77

    Hence, the correct answer is option C.

    (ii) Given here,

    A.P. = -3, -1/2, ,2 …

    Therefore, we can find,

    First term a = – 3

    Common difference, d = a2 − a1 = (-1/2) -(-3)

    ⇒(-1/2) + 3 = 5/2

    As we know, for an A.P.,

    an = a+(n−1)d

    Putting the values;

    a11 = 3+(11-1)(5/2)

    a11 = 3+(10)(5/2)

    a11 = -3+25

    a11 = 22

    Hence, the answer is option B.

    • 0
Leave an answer

Leave an answer

Browse

Choose from here the video type.

Put Video ID here: https://www.youtube.com/watch?v=sdUUx5FdySs Ex: "sdUUx5FdySs".

Captcha Click on image to update the captcha.