New Enroll in RBI Grade B New Batch - Starts on May 21

    Question

    The expression 12x - x² - 20 is positive between which

    values of x?
    A 2 > x > 10 Correct Answer Incorrect Answer
    B 2 < x < 10 Correct Answer Incorrect Answer
    C 2 ≤ x ≤ 10 Correct Answer Incorrect Answer
    D 2 ≥ x ≥ 10 Correct Answer Incorrect Answer

    Solution

    ATQ,

    So, 12x - x² - 20 > 0

    Or, x² - 12x + 20 < 0

    Or, x² - 10x - 2x + 20 < 0

    Or, x(x - 10) -2(x - 10) < 0

    Or, (x - 2)(x - 10) < 0

    So, x = 2 or x = 10

    So, the expression is positive between 2 and 10.

    Practice Next