solve a system with matrix inverses or augmented matrices
Grade 11 Math Worksheet

Circle the best answer, or write your answer on the line.
Zee writes the system 3y + 2x = 8 and x − 4y = 1 as AX = B. Which matrix equation is it?
- [2, 3; 1, -4][8; 1] = [x; y]
- [2, 3; 1, 4][x; y] = [8; 1]
- [2, 3; 1, -4][x; y] = [8; 1]
- [3, 2; 1, -4][x; y] = [8; 1]
- [2, 1; 3, -4][x; y] = [8; 1]
3x + 5y = 13; x + 4y = 2. Number table A = [3, 5; 1, 4]. Pia solves the system in the figure with X = A⁻¹B, where A⁻¹ = (1/7)[4, -5; -1, 3] and B = [13; 2]. What is x?
Esme replaces row 2 of [1, 3 | 7; 4, 5 | 6] with row 2 − 4 × row 1. What is the new number in row 2, after the bar?
Pia solves 2x + 5y = 16 and x + 3y = 10 with X = A⁻¹B. What is y?
Ren solves 3x + 4y = 5 and 2x + 5y = 8 with X = A⁻¹B. What is x?
Tala solves 4x + y = 5 and 3x + 2y = 0 with X = A⁻¹B. What is y?
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Start
[1, 2, -1 | 7; 2, 5, 1 | 24; 1, 5, 9 | 39]. Row steps: row 2 − 2 × row 1, then row 3 − row 1, then row 3 − 3 × row 2.
Tala row-reduces the system in the figure to the last table [1, 2, -1 | 7; 0, 1, 3 | 10; 0, 0, 1 | 2]. What is y?
Start
[1, 1, 2 | 11; 3, 4, 3 | 16; 2, 3, 2 | 10]. Row steps: row 2 − 3 × row 1, then row 3 − 2 × row 1, then row 3 − row 2.
Zee row-reduces the system in the figure to the last table [1, 1, 2 | 11; 0, 1, -3 | -17; 0, 0, 1 | 5]. What is y?
Start
[1, 2, -1 | 5; 4, 9, -1 | 32; 3, 8, 4 | 41]. Row steps: row 2 − 4 × row 1, then row 3 − 3 × row 1, then row 3 − 2 × row 2.
Ari row-reduces the system in the figure to the last table [1, 2, -1 | 5; 0, 1, 3 | 12; 0, 0, 1 | 2]. What is x?
Start
[1, 3, 2 | 11; 2, 7, 2 | 15; 5, 16, 9 | 51]. Row steps: row 2 − 2 × row 1, then row 3 − 5 × row 1, then row 3 − row 2.
Bo row-reduces the system in the figure to the last table [1, 3, 2 | 11; 0, 1, -2 | -7; 0, 0, 1 | 3]. What is x?