using_sage/questions.rst
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     1 Objective
       
     2 ---------
       
     3 
       
     4 1. How do you find the limit of the function ``x/sin(x)`` as ``x`` tends to
       
     5    ``0`` from the negative side.
       
     6 
       
     7    Answer: lim(x/sin(x), x=0, dir="below")
       
     8 
       
     9 #. Find the third differential of the function ``exp(sin(x)*cos(x^2))``
       
    10  
       
    11    Answer: diff(exp(sin(x)*cos(x^2), x, 3)
       
    12 
       
    13 #. Solve the system of linear equations::
       
    14 
       
    15      x-2y+3z = 7
       
    16      2x+3y-z = 5
       
    17      x+2y+4z = 9
       
    18 
       
    19    Answer::
       
    20 
       
    21      A = Matrix([[1, -2, 3], 
       
    22                  [2, 3, -1], 
       
    23                  [1, 2, 4]])
       
    24 
       
    25      b = vector([7, 5, 9])
       
    26 
       
    27      solve_right(A, b)
       
    28 
       
    29 #. How do you get the factorized form of ``x^4 - 4x^2 + x^3 + 2x + 7`` 
       
    30 
       
    31    Answer::
       
    32 
       
    33       factor( x^4 + x^3 - 4*x^2 + 2*x + 7 )
       
    34 
       
    35 #. list all the primes between 2009 and 2900
       
    36 
       
    37    Answer: prime_range(2009, 2901)
       
    38 
       
    39 #. Which function is used to check primality
       
    40 
       
    41    a. isPrime
       
    42    #. isprime
       
    43    #. is_prime
       
    44    #. prime
       
    45 
       
    46    Answer: is_prime
       
    47 
       
    48 #. How do you list all the combinations of ``[1, 2, 3, 4]``
       
    49 
       
    50 
       
    51    Answer::
       
    52 
       
    53      c1 = Combinations([1, 2, 3, 4])
       
    54      c1.list()
       
    55 
       
    56 #. How do you list all the permutations of ``[1, 3, 2, 3]``
       
    57 
       
    58     Answer::
       
    59 
       
    60       p1 = Permutations([1, 3, 2, 3])
       
    61       p2.list()
       
    62 
       
    63 
       
    64 Programming
       
    65 -----------
       
    66 
       
    67 1. Obtain the sum of primes between 1 million and 2 million. 
       
    68 
       
    69    Answer::
       
    70 
       
    71      prime_sum = 0
       
    72      for i in range(1000001, 2000000, 2):
       
    73          if is_prime(i):
       
    74          prime_sum += i
       
    75         
       
    76      prime_sum
       
    77 
       
    78    OR
       
    79    ::
       
    80 
       
    81      sum(prime_range(1000000, 2000000))
       
    82 
       
    83 2. ``graphs.WorldMap()`` gives the world map in the form of a
       
    84    graph. ::
       
    85 
       
    86        G = graphs.WorldMap()
       
    87        G.vertices()
       
    88 
       
    89   
       
    90    Suppose, I wish to go from India to France by Road, find out the
       
    91    least number of Visas that I'll have to obtain. 
       
    92 
       
    93    Answer::
       
    94 
       
    95       G.distance("India", "France")
       
    96 
       
    97       
       
    98 
       
    99