Determine which of the matrices in Exercises 1–6 are symmetric. 3.

In Exercises 5–8, use the definition of Ax to write the matrix equation as a vector equation, or vice versa. 5. 5 1 8 4 -2 -7 3 −5 5 -1 3 -2 = -8 - [18] 16

In Exercises 13–18, perform each matrix row operation and write the new matrix. -6 4| 10 13. 1 5 -5 3 4 7 -12 6 9 40 3. 14. 1 -4 7|4 2 0 -1 |7 1 3 -3 15. 1 -3R, + R, -2 -1 -9- -9- 16. 3 3 -1 10 -3R + R2 1 3 5 1 -1 1 1 3. 1 -2 -1 17. 2 4| 11 -2R, + R3 5 1 6. -5R, + R4 1 -5 2 -2 4 -3 -1 18. 3 2 -1 -3R + R3 -4 4 2-3 4R, + R4 -len すす 2. 1. 2. 1. 3.