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MATH 1324 Quiz 12 Show all work in the space provided. Credit will be given only

ID: 3113947 • Letter: M

Question

MATH 1324

Quiz 12

Show all work in the space provided. Credit will be given only for work that is clear and readable.

1. Let A= [ 3 -4 0 B= [0 -4 C=[1 -2 D=[7 1

1 x 2 ] -2 3 5 7] -3 0]

1 y]

. Perform the indicated operations

a) 2C-3D

a) ­­­­­­­­­­­­­­­­­­­­­­__________________

b) AB

b) ­­­­­­­­­­­­­­­­­­­­­­__________________

c) BA

c) ­­­­­­­­­­­­­­­­­­­­­­__________________

d) AC

d) ­­­­­­­­­­­­­­­­­­­­­­__________________

2. A company makes gizmos, gadgets, and widgets. Each gizmo requires 3 hours of painting, 4 hours of trimming and 1 hour of packaging to produce. Each gadget requires 2 hours of painting, 5 hours of trimming and 2 hours of packaging. Each widget requires 4 hours of painting, 2 hours of trimming, and 3 hours of packaging. Form a 3X3 matrix, H, summarizing this information as follows.

The company has plants in Louisiana and New Jersey. In Louisiana, the paint shop pays $9/hr., the trim shop pays $8.50/hr., and the packing shop pays $7.25/hr. In New Jersey, the paint shop pays $9.50 /hr., the trim shop pays $9/hr., and the packing shop pays $8.38/hr. Summarize this information in a matrix W, such that the product HW is doable mathematically and makes sense within the context of the problem.

Compute the matrix HW and interpret each entry.

3. A decorator wants to purchase plants for a new home. She is interested in three types of plants costing $7, $10, and $13 each. If she has budgeted exactly $150 for the plants and wants to purchase exactly 15 of them, what are her options?  List or make a chart of ALL options.  

Explanation / Answer

1. a. 2C-3D

2C= 2 [ 1 -2 = [2 -4

5 7] 10 14]

3D = 3[7 1 = [21 3

-3 0] -9 0 ]

2C-3D = [2 -4 - [21 3 = [2-21 -4-3 = [-19 -7

10 14] -9 0] 10-(-9) 14-0] 19 14]

B. AB

A= [3 -4 0 B = [0 -4

1 x 2] -2 3

1 y]

AB = [3*0+-4*-2+0*1 3*-4+-4*3+0*y = [8 -24

1*0+x*-2+2*1 1*-4+x*3+2*y] -2x+2 -4+3x+2y]

BA=

B= [0 -4 A= [3 -4 0

-2 3 1 x 2]

1 y]

BA = [0*3+-4*1 0*-4+-4*x 0*0+-4*2 = [ 4 -4x -8

-2*3+3*1 -2*-4+3*x -2*0+3*2 -3 8+3x 6

1*3+y*1 1*-4+y*x 1*0+y*2] 3+y -4+xy 2y]

AC=

A= [3 -4 0 C = [1 -2

1 x 2] 5 7]

AC= not possible. number of column of the 1st matrix must be equal to the number of the rows of the 2nd matrix.