New Enroll in RBI Gr B 2025 Exclusive New Batch on March 18

    Question

    In each of the following questions a number series is given. One term of the series is denoted by 'x' . You have to calculate the value of 'x' and by using the value of 'x' , you have to replace the question mark (?) in the following questions :

    If2.53.5 x 30124625 Then, x ² - 1 - 2x =

    ?
    A 80 Correct Answer Incorrect Answer
    B 75 Correct Answer Incorrect Answer
    C 62 Correct Answer Incorrect Answer
    D 92 Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    2.5× 1 + 1 = 3.5 3.5 × 2 + 2 = 9 9× 3 + 3 = 30 30×4 + 4 = 124 124×5 + 5 = 625 Hence, x= 9 Hence, x2 -1-2x= 92-1 - 2×9 = 81 - 1 – 18 = 62

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