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CBSE Class 10 Mathematics Exam 2018: Important 4 Marks Questions

Feb 22, 2018 13:23 IST
    CBSE Class 10 Mathematics Important 4 Marks Questions
    CBSE Class 10 Mathematics Important 4 Marks Questions

    In this article we are providing the CBSE Class 10 Mathematics: Important 4 Marks Questions to prepare for the board exam 2018. All these questions are completely solved.

    In CBSE Class 10 Mathematics Board Exam 2018, Section - D will comprise 8 questions of 4 marks each.

    All these Class 10 Mathematics: Important 4 Marks Questions have been prepared after carrying the thorough analysis of the trend followed in previous years’ board exams and the latest syllabus. Questions have been picked from the most important topics of class 10 Maths. Thus practicing these questions will help cover the important part of the curriculum thus making an effective preparation for the board exams 2018. Moreover, the solutions provided here will give an idea to present your answers in the best way to grab maximum scores.

    CBSE Class 10 Mathematics Board Exam 2018: Latest Exam Pattern

    Given below are some sample questions for CBSE Class 10 Mathematics: Important 4 Marks Questions:

    Q. For any positive integer n, prove that n3 – n is divisible by 6.

    Solution.

    = product of three consecutive positive integers.

    Now, we have to show that the product of three consecutive positive integers is divisible by 6.

    We know that any positive integer n is of the form 3q, 3q + 1 or 3q + 2 for some positive integer q.

    Now three consecutive positive integers are n, n + 1, n + 2.  

    Case I. If n = 3q.

    n(n + 1) (n + 2) = 3q(3q + 1) (3q + 2)

    But we know that the product of two consecutive integers is an even integer.

    ∴ (3q + 1) (3q + 2) is an even integer, say 2r.

    n(n + 1) (n + 2) = 3q × 2r = 6qr, which is divisible by 6.

    Case II. If n = 3n + 1.

    ∴ n(n + 1) (n + 2) = (3q + 1) (3q + 2) (3q + 3)

                                 = (even number say 2r) (3) (q + 1)

                                 = 6r (q + 1),

    which is divisible by 6.

    Case III. If n = 3q + 2.

    ∴ n(n + 1) (n + 2) = (3q + 2) (3q + 3) (3q + 4)

                                 = multiple of 6 for every q

                                 = 6r (say),

    which is divisible by 6.

    Hence, the product of three consecutive integers is divisible by 6.

    CBSE Class 10 Mathematics Exam 2018: Important 3 Marks Questions

    Q. The first and the last terms of an AP are 10 and 361 respectively. If its common difference is 9 then find the number of terms and their total sum?

    Sol.

    Given, first term, a = 10

    Last term, al = 361

    And, common difference, d = 9

    al =a + (n −1)
    361 = 10 + (n − 1)9
    361 = 10 + 9n − 9
    361 = 9n + 1
    9n = 360
    n = 40

    Therefore, total number of terms in AP = 40

    Now, sum of total number of terms of an AP is given as:

    Sn = n/2 [2a + (n − 1)d]
    S40 = 40/2 [2 x 10 + (40 − 1)9]
          = 20|20 + 39 x 9]
          =20[20 + 351]
          =20 x 371 = 7420

    Thus, sum of all 40 terms of AP = 7420

    To get the complete set of questions, click on the following link:

    CBSE Class 10 Mathematics: Important 4 Marks Questions

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