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    I basically have no idea how to start this question, it's part A of an exam question for numerical analysis and just don't know how to even start it... and the mark scheme (even though uni level ones are useless, isn't available..)

    I've got examples with lagrange polynomials where they give you points but I can't seem to make the connection..


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    Well, you know what n-1 distinct roots of L_k are, so since it has degree n-1, you can write down that L_k(x) = C (x-\alpha_1)(x- \alpha_2)...(x-\alpha_{n-1}) where the \alpha_i terms are the roots of L_k and C is a constant that you need to find.

    Then to find the constant you use the fact that L_k(x_k) = 1.

    (This is all bookwork you'd be expected to know - something has gone wrong with either your lecture schedule or study habits if you are trying to do this question without knowing anything about the topic).
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    (Original post by 0range)
    I basically have no idea how to start this question, it's part A of an exam question for numerical analysis and just don't know how to even start it... and the mark scheme (even though uni level ones are useless, isn't available..)

    I've got examples with lagrange polynomials where they give you points but I can't seem to make the connection..


    You know the formula for Lagrange polynomials? Then in the first part, you are given n points, and so you can find the polynomial of degree n-1 that goes through these n points.
 
 
 

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