C Challenge

Find the values of x and y that make each equation true.

31. [ 0 x 2 x − 4 ] + [ 3 4 y y 8 ] = [ 3 18 1 4 ] . matrix with 2 rows and 2 columns , row1 column 1 , 0 , column 2 x , row2 column 1 , 2 x , column 2 negative 4 , end matrix . plus . matrix with 2 rows and 2 columns , row1 column 1 , 3 , column 2 4 y , row2 column 1 , y , column 2 8 , end matrix . equals . matrix with 2 rows and 2 columns , row1 column 1 , 3 , column 2 18 , row2 column 1 , 1 , column 2 4 , end matrix
32. [ x − 1 4 3 x ] + [ − 3 y 5 − 6 2 y ] = [ 7 4 − 2 10 ] . matrix with 2 rows and 2 columns , row1 column 1 , x , column 2 negative 1 , row2 column 1 , 4 , column 2 3 x , end matrix . plus . matrix with 2 rows and 2 columns , row1 column 1 , negative 3 y , column 2 5 , row2 column 1 , negative 6 , column 2 2 y , end matrix . equals . matrix with 2 rows and 2 columns , row1 column 1 , 7 , column 2 4 , row2 column 1 , negative 2 , column 2 10 , end matrix

Standardized Test Prep

SAT/ACT

33. Which matrix is equal to − 3 [ 5.5 − 1 − 3 2 ] ? negative 3 . matrix with 2 rows and 2 columns , row1 column 1 , 5.5 , column 2 negative 1 , row2 column 1 , negative 3 , column 2 2 , end matrix . question mark
    1. [ 8.5 2 0 5 ] . matrix with 2 rows and 2 columns , row1 column 1 , 8.5 , column 2 2 , row2 column 1 , 0 , column 2 5 , end matrix
    2. [ 2.5 − 4 − 6 − 1 ] . matrix with 2 rows and 2 columns , row1 column 1 , 2.5 , column 2 negative 4 , row2 column 1 , negative 6 , column 2 negative 1 , end matrix
    3. [ 16.5 − 3 − 9 6 ] . matrix with 2 rows and 2 columns , row1 column 1 , 16.5 , column 2 negative 3 , row2 column 1 , negative 9 , column 2 6 , end matrix
    4. [ − 16.5 3 9 − 6 ] . matrix with 2 rows and 2 columns , row1 column 1 , negative , 16.5 , column 2 3 , row2 column 1 , 9 , column 2 negative 6 , end matrix
34. Which equation represents a line parallel to the graph of y = 3 x + 6 ? y equals 3 x plus 6 question mark
    6. x − 1 3 y = 0 x minus , 1 third , y equals 0
    7. y = − 3 x + 2 y equals negative 3 x plus 2
    8. y = 1 3 x + 2 y equals , 1 third , x plus 2
    9. y = 2 x + 6 y equals 2 x plus 6
35. What is the simplified form of 2 108 ? 2 , square root of 108 , question mark
    1. 12 3 12 square root of 3
    2. 6 12 6 square root of 12
    3. 3 26 3 square root of 26
    4. 2 6 2 square root of 6

Short Response

36. Carlos does his homework at a rate of 25 problems per hour. Cecelia does her homework at a rate of 30 problems per hour. Carlos started his homework 12 min before Cecelia. How many hours after Carlos started his homework will they have done the same number of problems? Show your work.

Mixed Review

See Lesson 11-7.

Identify the excluded value of each rational function.

37. y = 3 x − 5 y equals . fraction 3 , over x minus 5 end fraction
38. y = − 1 x y equals , negative 1 over x
39. f ( x ) = 5 x x − 4 f , open x close , equals . fraction 5 x , over x minus 4 end fraction

Get Ready! To prepare for Lesson 12-2, do Exercises 40 and 41.

See Lesson 5-7.

For each table, make a scatter plot of the data. Tell whether a correlation exists. If so, tell whether the correlation reflects a causal relationship. Explain your reasoning.

40. Shoe Sizes and Test Scores

    Name	Shoe Size	Test Score
    Baker	9	87
    Johns	11	94
    Rivera	8	96
    Samuels	7	75

41. Sales Commissions

    Employee	Products Sold	Commission Earned ($)
    Andrews	38	310
    Garcia	24	250
    Jordan	47	448
    Walker	53	495

Table of Contents