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The solutions to a linear algebra final exam from dawson college, mathematics department. The exam covers topics such as solving linear systems using gauss-jordan method, determining the number of solutions, matrix multiplication, and vector projection.
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1 2 3 4
1 2 3 4
1 2 3 4
x x x x
x x x x
x x x x
Ans. x 1 (^) 1 3 t , x 2 2 t , x 3 3 , x 4 t
a) Exactly one solution, b) No solution, c) Infinitely many solutions
x y k z k
x y z
x y z
Ans. a) k 0 b) k 0 c) never
3 2 . Show that
A 2 A 3 A 2 I
1 2
Ans. AA A A A I A A A I
( 2 3 2 ) 2 3 2
1 2 3 2
( 2 3 2 ) 2 3 2
1 2 3 2
x y z
x y z
x y z
a) (5 marks) Find the inverse of the coefficient matrix
b) (3 marks) Use the result found in part a) to solve the system
Ans. a)
b) x 1 , y 3 , z 6
x y z
x y z
x y z
Ans. y 3
Ans.
T A B
1 det
1 det 2
A B
d) (5 marks) Let 5
g h i
d e f
a b c
. Find
f d i g c a
e d h g b a
d g a
Ans. a) 2
b) 3
c) 54 d) 30
. Find the vector