Chapter 1.1, Problem 15E

CCSS REASONING The number of subscribers using pagers in the United States can be modeled by f(x) = 0.015x4 -0.44x³ +3.46x² - 2.7x+9.68 where x is the number of years after 1990 and f(x) is the number of subscribers in millions. a. Graph the function. b. Describe the end behavior of the graph. c. What does the end behavior suggest about the number of pager subscribers? d. Will this trend continue indefinitely? Explain your reasoning.

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Name Assume there is the following simplified grade book: Homework Labs | Final Exam | Project Avery 95 98 90 100 Blake 90 96 Carlos 83 79 Dax 55 30 228 92 95 79 90 65 60 Assume that the weights used to compute the final grades are homework 0.3, labs 0.2, the final 0.35, and the project 0.15. | Write an explicit formula to compute Avery's final grade using a single inner product. Write an explicit formula to compute everyone's final grade simultane- ously using a single matrix-vector product.

1. Explicitly compute by hand (with work shown) the following Frobenius inner products 00 4.56 3.12 (a) ((º º º). (156 (b) 10.9 -1 0 2)), Fro 5')) Fro

3. Let 4 0 0 00 0 0 1.2 0 00 0 0 0 -10.1 0 0 0 D = 0 0 0 00 0 0 0 0 05 0 0 0 0 0 0 2.8 Either explicitly compute D-¹ or explain why it doesn't exist.

4. [9 points] Assume that B, C, E are all 3 x 3 matrices such that BC == -64 -1 0 3 4 4 4 -2 2 CB=-1-2 4 BE -2 1 3 EC = 1 3 2 -7, 1 6 -6 2-5 -7 -2 Explicitly compute the following by hand. (I.e., write out the entries of the 3 × 3 matrix.) (a) [3 points] B(E+C) (b) [3 points] (E+B)C (c) [3 points] ETBT

6. Consider the matrices G = 0 (3) -3\ -3 2 and H = -1 2 0 5 0 5 5 noting that H(:, 3) = 2H(:,1) + H(:, 2). Is G invertible? Explain your answer. Is H invertible? Explain your answer. Use co-factor expansion to find the determinant of H. (Hint: expand the 2nd or 3rd row)

For the matrix A = = ( 6 }) . explicitly compute by hand (with work shown) the following. I2A, where I2 is the 2 × 2 identity matrix. A-1 solving the following linear systems by using A-¹: c+y= 1 y = 1 (d) (e) (f) A² find the diagonal entries of A

If 3x−y=12, what is the value of 8x / 2y A) 212B) 44C) 82D) The value cannot be determined from the information given.