Multiply matrices, simplify matrix expressions and solve A + X = B

Answer Key - Grade 11 Math Worksheet - Challenge Me

Circle the best answer, or write your answer on the line.

1. 1.

   Row 1: 3, 12; row 2: -6, -15. Kira solves 3X = B for the matrix X. What is the entry in row 1, column 2 of X?

   4
2. 2.

   Row 1: 2, -8; row 2: 10, -4. Luz's matrix puzzle says -2X = B. What is the entry in row 2, column 1 of X?

   -5
3. 3.

   Row 1: -7, -8; row 2: 5, 6. Matrix B: row 1: 3, -2; row 2: 15, 14. Milo needs X, where 2X + A = B. What is the entry in row 2, column 2 of X?

   4
4. 4.

   Row 1: 3, -7; row 2: -6, 4. Matrix B: row 1: -12, 8; row 2: 6, 13. For 3X + A = B, what is the entry in row 1, column 1 of X, the matrix Noah wants?

   -5

5. Read this first

   Matrix A

   Row 1: -3, 2; row 2: -2, 4. Matrix B: row 1: 3, 5; row 2: 4, 2. Matrix C: row 1: -3, 3; row 2: -6, -1.

6. 5.

   Pia simplifies AB + C. What is the entry in row 1, column 2?

   -8

7. Matrix A

   Row 1: 2, -2; row 2: 4, 2. Matrix B: row 1: 5, -1; row 2: 1, 5. Matrix C: row 1: 4, -1; row 2: 4, -5.

8. 6.

   Tala works out A(B + C) for the matrices shown. What is its entry in row 2, column 2?

   -8

9. Matrix Q (rows Friday, Saturday; columns cookies, juices)

   Row 1: 35, 49; row 2: 35, 38. Matrix P (rows cookies, juices; columns price, cost to make, in dollars): row 1: $1, $0.40; row 2: $1.50, $0.60.

10. 7.

    An adult runs the snack table. Matrix Q counts snacks sold, and matrix P gives each snack's price and cost to make. Ari finds QP. What were Saturday's sales in dollars?

    $92

11. Matrix Q (rows Friday, Saturday; columns muffins, milks)

    Row 1: 30, 38; row 2: 45, 48. Matrix P (rows muffins, milks; columns price, cost to make, in dollars): row 1: $1.25, $0.50; row 2: $0.75, $0.30.

12. 8.

    An adult runs the snack table. Matrix Q counts snacks sold, and matrix P gives each snack's price and cost to make. Bo finds QP. What did Friday's snacks cost to make, in dollars?

    $26.40

13. Use this

    Matrix Q (rows first game, second game; columns popcorn bags, lemonades): row 1: 60, 58; row 2: 55, 45. Matrix P (rows popcorn bags, lemonades; columns price, cost to make, in dollars): row 1: $2, $0.75; row 2: $1.50, $0.50.

14. 9.

    An adult runs the snack table. Matrix Q counts snacks sold, and matrix P gives each snack's price and cost to make. Esme finds QP. What were the first game's sales in dollars?

    $207

15. Matrix Q (rows Monday, Tuesday; columns apples, waters)

    Row 1: 44, 29; row 2: 13, 29. Matrix P (rows apples, waters; columns price, cost to make, in dollars): row 1: $0.50, $0.20; row 2: $1, $0.25.

16. 10.

    An adult runs the snack table. Matrix Q counts snacks sold, and matrix P gives each snack's price and cost to make. Jun finds QP. What did Tuesday's snacks cost to make, in dollars?

    $9.85