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


    Question

    Find the values of 'a' and 'b', so that the polynomial

    x3 βˆ’ ax2 βˆ’ 13x + b has (xβˆ’1) and (x+3) as factors:
    A a = 4, b = 5 Correct Answer Incorrect Answer
    B a = 3, b = 15 Correct Answer Incorrect Answer
    C a = 15, b = 3 Correct Answer Incorrect Answer
    D a = 5, b = 4 Correct Answer Incorrect Answer

    Solution

    Let (p(x)) = x3 βˆ’ ax2 βˆ’ 13x + b If (x - 1) and (x + 3) are factors of p(x), then p (l) = O and p (- 3) = O (1)3 βˆ’ a(1)2 – 13 x 1 + b = 0 and (βˆ’3)3 βˆ’ a(βˆ’3)2 βˆ’ 13(βˆ’3) + b = 0 1 βˆ’ a – 13 + b = 0 and βˆ’27– 9a+ 39 + b = 0 a – b = - 12 …..(1) and 9a – b = 12 …..(2) Subtracting the equation from first, we get (a - b) - (9a - b) = - 12 - 12 - 8a = - 24 a = 3 Putting a = 3 in (a - b) = -12, We get, b = 15

    Practice Next

    Relevant for Exams:

    ask-question

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

    Get My Free Call