πŸ“’ Too many exams? Don’t know which one suits you best? Book Your Free Expert πŸ‘‰ call Now!


    Question

    If x = (√13 + √12)/ (√13 - √12) and y = (√13 -

    √12)/(√13 + √12), then find the value of 4x2 – xy + 4y2.
    A 2361 Correct Answer Incorrect Answer
    B 2491 Correct Answer Incorrect Answer
    C 2721 Correct Answer Incorrect Answer
    D 2541 Correct Answer Incorrect Answer

    Solution

    4x2 – xy + 4y2 4(x2 + y2) – xy 4[(x + y)2 – 2xy] – xy 4(x + y)2 – 9xy ……..(1) x + y = [(√13 + √12)/(√13 - √12)] + [(√13 - √12)/(√13 + √12)] = [(√13 + √12)2 + (√13 - √12)2]/((√13)2 - (√12)2) = [13 + 12 + 2(√13)(√12) + 13 + 12 - 2(√13)(√12)]/2 = 25 Β  xy= [(√13 + √12)/(√13 - √12)][(√13 - √12)/(√13 + √12)] = 1 From eq (1) => 4(25)2 - 9 = 2491 Β 

    Practice Next
    ask-question

    Not sure which exam is best for you Talk to our expert

    Get My Free Call