Math 220 Assignment

September 24, 2001

Assignment for Wednesday, September 26

Let G be the 4 \times 4 matrix

 
(
2
0
1
-2
-1
1
1
-1
4
2
5
5
7
-1
2
)
  , 

and let f be the linear map (or function) from R^{4} to R^{4} defined by the formula

  y  =  f(x)  =  G x  .  

  1. Solve each of the following systems of 4 linear equations in 4 unknowns x_{1}, x_{2}, x_{3} and x_{4}.

    1. f(x) = (0, 0, 0, 0).

    2. f(x) = (1, -1, 1, 3) with x_{3} = 0.

    3. f(x) = (1, -1, 1, 4) with x_{3} = 0.

    4. f(x) = (1, -1, 1, 4) with x_{3} = x_{4} = 0.

    5. f(x) = (3, -1, 2, 1) with x_{3} = 0.

    6. f(x) = (3, -1, 7, 10) with x_{3} = 0.

  2. Answer the following questions:

    1. What is the kernel of f ?

    2. Find equations that characterize the image of f.

  3. For each part of the first preceding problem if there are solutions find a solution s and a minimal set u, v, ... of vectors such that the most general solution of the system is the sum of s and an arbitrary linear combination of the vectors u, v, ....


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