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

Answer Key - Grade 11 Math Worksheet

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

1. Read this first

   Matrix A

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

2. 1.

   Ren multiplies matrices A and B. What is the entry in row 1, column 2 of AB?

   -19

3. Matrix A

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

4. 2.

   What is the entry in row 2, column 2 of AB, the product Zee is working on?

   9

5. Matrix A

   Row 1: 2, 1, -2; row 2: -5, -9, -1. Matrix B: row 1: -8, 5, 9; row 2: -2, 8, -9.

6. 3.

   Milo finds X so that A + X = B. What is the entry in row 1, column 3 of X?

   11

7. Matrix A

   Row 1: 2, 2; row 2: 5, 8; row 3: -6, 8. Matrix B: row 1: 4, -3; row 2: 12, 4; row 3: 1, -2.

8. 4.

   Noah solves the matrix equation A + X = B. What is the entry in row 3, column 1 of X?

   7

9. Matrix A

   Row 1: 6, 1, 5; row 2: -4, -5, 7. Matrix B: row 1: 4, -5, 12; row 2: -9, 8, -8.

10. 5.

    Pia needs the matrix X with A + X = B. What is the entry in row 2, column 2 of X?

    13

11. Matrix A

    Row 1: -7, -5; row 2: -8, 3; row 3: -1, 5. Matrix B: row 1: 11, -9; row 2: -1, 5; row 3: -7, 8.

12. 6.

    In Ren's puzzle, A + X = B. What number goes in row 1, column 2 of X?

    -4
13. 7.

    Row 1: -3, 2; row 2: 5, 5. Matrix B: row 1: 1, 3; row 2: 4, -4. Tala multiplies the 2 × 2 matrices A and B. Which matrix is AB?

    • rows (5, -17) and (-25, -5)
    • rows (-3, 6) and (20, -20)
    • rows (12, 17) and (-32, -12)
    • rows (5, -17) and (25, -5)
14. 8.

    Row 1: 4, 1; row 2: -3, -3. Matrix B: row 1: 2, -4; row 2: 1, 3. Zee needs the product AB for a puzzle. Which matrix is AB?

    • rows (9, -13) and (-9, 3)
    • rows (20, 14) and (-5, -8)
    • rows (8, -4) and (-3, -9)
    • rows (9, -13) and (9, 3)
15. 9.

    Row 1: 3, 4; row 2: 2, 3. Matrix B: row 1: 4, 4; row 2: 4, 2. Which matrix is AB, the product Esme is finding?

    • rows (12, 16) and (8, 6)
    • rows (20, 28) and (16, 22)
    • rows (28, 20) and (20, 14)
    • rows (28, 20) and (-20, 14)
16. 10.

    Row 1: 2, -3; row 2: 2, -1. Matrix B: row 1: 5, -4; row 2: -2, -2. Jun checks a homework answer for AB. Which matrix is AB?

    • rows (2, -11) and (-8, 8)
    • rows (16, -2) and (12, -6)
    • rows (16, -2) and (-12, -6)
    • rows (10, 12) and (-4, 2)