Compute the determinants in Exercises 1-8 using a cofactor ex- Add the downward diagonal products and subtract the up- pansion across the first row. In Exercises 1-4, also compute the ward products. Use this method to compute the determinants in determinant by a cofactor expansion down the second column. Exercises 15-18. Warning: This trick does not generalize in any reasonable way to 4 x 4 or larger matrices. O NUC 0 0 3 ONW 15. 3 16. 4 -5 0 5 -2 3 4 4. -3 3 A 17. -NW 18. 2 W WI AWN ANN HOWWAN www I WAR NOW NWE 5 ON 6. In Exercises 19-24, explore the effect of an elementary row operation on the determinant of a matrix. In each case, state the row operation and describe how it affects the determinant. WNO OWN 7 Compute the determinants in Exercises 9-14 by cofactor expan- sions. At each step, choose a row or column that involves the least [e a ] [ke ka ] amount of computation. 0 21. [3 2 ]. [stok 4 21] N vous 10 UNION - O 22 . [a b ], [atke b+ kd d WNJW NNO- AWOO WWWP baNO Of ON 11. OOOW 12 wooo 23 UNO 13. OUNOA NOUOO OOWOO OONU WOMAN bMANY ONWA NOVHA HNAOW WUIWA Compute the determinants of the elementary matrices given in Exercises 25-30. (See Section 2.2, Examples 5 and 6.) OO -OO NWOOM 0 25 26. 14. O k 1 0 07 0 0 27. 28. 0 0 The expansion