Math 324: Assignment 7
Instructions. The following six exercises plus a written solution to the exercise you select to
present in class are due on Monday, November 1.
1. Evaluate the determinant of
0 1 1
1 2 −5
6−4 3
by:
(a) using the cofactor expansion along the first column;
(b) using the cofactor expansion along the first row.
2. Evaluate the determinant of
1 0 −2 3
−3 1 1 2
0 4 −1 1
2 3 0 1
by
(a) using elementary row operations to make the first entries in rows 2 and 4 both 0, and then
using the cofactor expansion along the first column.
(b) using elementary row operations to make the matrix upper triangular.
3. Do exercise 3. on p. 221.
4. Do exercise 4. on p. 221.
5. Consider the system of equations
3x+y+z= 4
−2x−y= 12
x+ 2y+z=−8
Using MathCAD, solve
this system by
(a) row reducing the agmented matrix;
(b) using the inverse of the coefficient matrix;
(c) using Cramer’s rule.
6. Do exercise 2. on p. 228.
See the reverse side for in-class presentation exercises.
