Exam3
- Page ID
- 218477
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Math 203 Practice Midterm 3
Please work out each of the given problems. Credit will be based on the steps towards the final answer. Show your work. Do your work on your own paper.
Problem 1 A physicist has plotted the position of a projectile over time. Based on Newton’s laws, the projectile should ideally travel in a parabolic path. Use matrices to find the most likely equation of this parabola. (You may use a calculator, but show the matrices that are being manipulated).
Problem 2 A new species of fish is introduced into the Truckee River. Initially 2 fish were stocked. It takes one year for this species to spawn, when each fish averages 3 successful children each year. (So there are 2 at the beginning, 2 at the end of the first year, 8 at the end of the second year, 14 at the end of the third year, etc.)
A. Assuming no fish die, set up a recursion relationship that gives the number of fish wn at the end of year n. Solution
B. Find a matrix A such that wn-1 = An-1(w0, w1)T . Solution
C. Find a diagonal matrix D such that A is similar to D.
Problem 3
Let V be the subspace of differentiable functions spanned by {ex, e2x, e3x} and let
L: V ---> V
be the linear transformation with L(f(x)) = f ''(x) - 3f '(x) + 2f(x)
A. Write down the matrix AL with respect to the given basis. Solution
B. Find the a basis for the kernel and range of L.
Problem 4 Let W = Span{(1,1,0,1), (0,1,2,3)}. Find a basis for the orthogonal complement of W.
Problem 5 Let \( A = \begin{pmatrix} 0 & 2 \\ -2 & 0 \end{pmatrix} \) and \( b = \begin{pmatrix} -2 \\ 1 \end{pmatrix} \) and T be the affine transformation T(x) = Ax + b . Sketch the image under T of the figure below.
Problem 6
Let L: V ---> V be a linear transformation. Use the fact that dim(Ker L) + dim(Range L) = dim(V)
to show that if L is one to one then L is onto.
Problem 7
Let A and B be matrices and let v be an eigenvector of both A and B. Prove that v is an eigenvector of the product AB.
Problem 8 Answer True of False and explain your reasoning.
A. Let A be a 3x3 matrix such that the columns of A form an orthonormal set of vectors. Then
\( A^T A \begin{pmatrix} 4 \\ -1 \\ 2 \end{pmatrix} = \begin{pmatrix} 4 \\ -1 \\ 2 \end{pmatrix} \)
B. Let V be the vector space of continuous functions then the expression <f, g> = f(1) + g(1) defines an inner product on V. |


