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  • Question in Andreas's workspace by Andreas Vohns and 1 other

    This is the question for week 9 of the MA100 course at the LSE. It looks at material from chapters 17 and 18.

    Description of variables for part b:
    For part b we want to have four functions such that the derivative of one of them, evaluated at 0, gives 0; but for the rest we do not get 0. We also want two of the ones that do not give 0, to be such that the derivative of their sum, evaluated at 0, gives 0; but when we do this for any other sum of two of our functions, we do not get 0. Ultimately this part of the question will show that even if two functions are not in a vector space (the space of functions with derivate equal to 0 when evaluated at 0), then their sum could nonetheless be in that vector space. We want variables which statisfy:

    a,b,c,d,f,g,h,j,k,l,m,n are variables satisfying

    Function 1: x^2 + ax + b sin(cx)
    Function 2: x^2 + dx + f sin(gx)
    Function 3: x^2 + hx + j sin(kx)
    Function 4: x^2 + lx + m sin(nx)

    u,v,w,r are variables satifying

    The derivatives of each function, evaluated at zero, are:
    Function 1: u
    Function 2: v
    Function 3: w
    Function 4: r

    So we will define
    u as random(-5..5 except(0))
    v as -u
    w as 0
    r as random(-5..5 except(0) except(u) except(-u))

    Then the derivative of function 3, evaluated at 0, gives 0. The other functions give non-zero.
    Also, the derivative of function 1 + function 2 gives 0. The other combinations of two functions give nonzero.

    We now take b,c,f,g,j,k,m,n to be defined as \random(-3..3 except(0)).
    We then define a,d,h,l to satisfy

    Description for variables of part e:

    Please look at the description of each variable for part e in the variables section, first.
    As described, the vectors V3_1 , V3_2 , V3_3 are linearly independent. We will simply write v1 , v2 , v3 here.
    In part e we ask the student to determine which of the following sets span, are linearly independent, are both, are neither:

    both: v1,v2,v3
    span: v1,v1+v2,v1+v2+v3, v1+v2+v3,2*v1+v2+v3
    lin ind: v1+v2+v3
    neither: v2+v3 , 2*v2 + 2*v3
    neither: v1+v2,v1-v2,v1-2*v2,2*v1-v2

  • Question in Andreas's workspace by Andreas Vohns and 3 others

    This question provides a list of data to the student. They are asked to find the mean, median, mode and range.