New RBI Grade B 2025 Notification will come Soon! Enroll Here

    Question

    How many integer pairs (x, y) satisfy the inequality

    x2 + 4y2 < 100?
    A 95 Correct Answer Incorrect Answer
    B 90 Correct Answer Incorrect Answer
    C 147 Correct Answer Incorrect Answer
    D 180 Correct Answer Incorrect Answer

    Solution

    y will lie in the range [-4, 4] When y = 4 or – 4, x will lie in the range [-5, 5] = 11 values. Total pairs = 22 When y = 3 or – 3, x will lie in the range [-7, 7] = 15 values. Total pairs = 30 When y = 2 or – 2, x will lie in the range [-9, 9] = 19 values. Total pairs = 38 When y = 1 or – 1, x will lie in the range [-9, 9] = 19 values. Total pairs = 38 When y = 0, x will lie in the range [-9, 9] = Total 19 pairs. Total pairs = 22 + 30 + 38 + 38 + 19 = 147

    Practice Next