Math 129 Test 3 Name Directions: You may use the book but you may not receive help from any other person or any computer site. You may not collaborate with any other person. You must use the methods and the notation of the course, give all the formulas that you use, and show all relevant work or you will receive NO CREDIT. Trial-and error is not an acceptable method of solution for any problem. Be sure to write your name on all the pages that you are turning in and staple the pages together. Be sure to show your work clearly and legibly. You must return the question page with your papers, and you must sign the statement at the end of the question page. Staple the question page to the front of the pages that you are turning in. DUE Wednesday JULY 3 AT THE BEGINNING OF CLASS.
1. A person has a hank account which currently contains $5000 and is earning interest at a rate of 4% per year compounded quarterly. lie plans to deposit $500 per quarter into this account for the next 8 years. If he doesn't take any money out, how much will he have in this account at the end of the 8 years? 2. A car cost $24,000. The purchaser made a down payment of $6000. The balance will he paid off in 48 equal monthly payments. The interest rate is 7.5% per year compounded monthly. Find the amount of each payment and also the amount of the loan that will he still owed after 1 year. [ —42 3 — 5 — 2 1 0 1 — 9 1 3. Given A = , B = [ 4 and C = [ . Find (If any one of 2 these is not defined, write NOT DEFINED as your answer to that part of the problem): (a) 3AI' (b) A— B (c) AC (d) CA 4. Solve using matrices and row-reduction. If there is no solution, indicate why. If there are an infinite number of solutions, give the general form of the solution.
x+2y+ 4z = 5 2x + 3y + z = 3 x + 3y + 11z = 12
5. Given the following system of equations:
x+ y + 2z = 2 2x + 3y + 2z = 1 2x+ 7z = 5
(a) Find the inverse of the coefficient matrix by using row-reduction. (b) Use the definition of an inverse to check that the matrix which you have just found is the desired inverse.
(c) Use the inverse matrix which you have found to solve the original system of equa-tions. STATEMENT: I, the undersigned, state that what I am submitting is entirely my own work. SIGNATURE: