M340L Practice 3rd Midterm (From November, 1993)

Problem 1: Consider the linear operator tex2html_wrap_inline25 ,
L(p(t)) = (t+1)p'(t) - 2p(t). As usual, tex2html_wrap_inline29 is the space of 2nd order polynomials in the variable t.

a) What is the matrix of L relative to the basis tex2html_wrap_inline35 ?

b) Find the dimension of the kernel of L and the dimension of the range of L.

c) Find a basis for the kernel of L. Also, find a basis for the range of L.

Problem 2 This problem concerns changing bases in tex2html_wrap_inline45 . Let S be the standard basis. Let tex2html_wrap_inline49 be another basis, where tex2html_wrap_inline51 , tex2html_wrap_inline53 , tex2html_wrap_inline55 .

a) Find a matrix P that converts from the T basis to the S basis. That is, so that for any vector X, tex2html_wrap_inline65 .

b) Find a matrix Q that converts from the S basis to the T basis. That is, so that for any vector X, tex2html_wrap_inline75 .

c) There is a linear operator L whose matrix, relative to the S basis, is tex2html_wrap_inline81 . Find the matrix of L relative to the T basis.

Problem 3. Let tex2html_wrap_inline87

a) What is the rank of A?

b) Find a basis for the null space of A.

c) Find a basis for the row space of A.

Problem 4. Let V be the span of tex2html_wrap_inline97 and tex2html_wrap_inline99 , where tex2html_wrap_inline101 , tex2html_wrap_inline103 and tex2html_wrap_inline105 .

a) Find an orthogonal basis for V.

b) Find an orthonormal basis for V.

Problem 5. True of False

a) The map tex2html_wrap_inline111 , L(x,y)=(x+y,y-1), is a linear transformation.

b) The map tex2html_wrap_inline111 , tex2html_wrap_inline117 , is a linear transformation.

c) The map tex2html_wrap_inline111 , L(x,y)=(3 x+ y,y-5x), is a linear transformation.

d) Let L be a linear transformation from tex2html_wrap_inline125 to tex2html_wrap_inline127 . If the rank of L is 3, then the kernel of L is 1-dimensional.

e) Let L be a linear transformation from tex2html_wrap_inline127 to tex2html_wrap_inline137 . If the kernel of L is 2 dimensional, then L is onto.

f) Let L be a linear transformation from tex2html_wrap_inline125 to tex2html_wrap_inline127 . If L is 1-1, then L is onto.

g) If a set of vectors is orthonormal, then it is a basis.

h) If a set of vectors is orthonormal, then it is linearly independent.

i) If a matrix is wider than it is tall (e.g. a tex2html_wrap_inline153 matrix), then the row rank is greater than the column rank.

j) Let L be a linear transformation from tex2html_wrap_inline157 to itself. The solutions (in tex2html_wrap_inline157 ) to the equation L(p)=0 form a vector space.




Fri Apr 4 16:25:02 CST 2003