Question 1
Consider the vectors p = i+j— 2k and q =i— 3j+12k
a) Find the unit vector in the direction of p.
b) Find the angle (in degrees) between p and q. Give you answer correct to 1 d.p.
[8]
Question 2
Consider the following matrices.
a) Given that C = AB, determine the element co.
[3]
b) Find (3A)?.
[3]
c) Is DB defined? If yes, then find it, and hence calculate tr(DB).
[7]
Question 3
Let A= ( aij ) be an n X n matrix.
a) When do we say that A is a symmetric matrix?
[2]
b) Prove that A+ A” is a symmetric matrix.
[5]
c) Prove that if A is an invertible symmetric matrix, then A~! is also symmetric.
[6]
Question 4
Consider the matrix A =
-1 1 2
3 0 —5
172
a) Use the Cofactor expansion method to evaluate the determinant of A.
b) Is A invertible? If it is, find Aq}.
[14]
c) Find det (3(2A)7?).
[6]