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MATH 210

KISII UNIVERSITY
UNIVERSITY EXAMINATIONS
SECOND YEAR EXAMINATION FOR THE AWARD OF
THE DEGREE OF BACHELOR OF SCIENCE, EDUCATION
FIRST SEMESTER 2021/2022
(FEBRUARY-JUNE, 2022)

MATH 210: LINEAR ALGEBRA I

STREAM: Y2 S1 TIME: 2 HOURS

DAY: TUESDAY, 9:00 AM – 11:00 AM DATE: 10/05/2022

INSTRUCTIONS:
1. Do not write anything on this question paper.
2. Answer Question ONE (Compulsory) and any other TWO Questions

QUESTION ONE (30 MARKS)

a. Consider the following systems of linear equation: (3 marks)


2𝑥 + 4𝑦 = 8
4𝑥 − 2𝑦 = 6
6𝑥 + 2𝑦 = 2𝑘
Find the value of 𝑘 for which the system is consistent

b. Use Gauss-Jordan Elimination method to solve the following systems of linear equations.
(6 marks)
3𝑥1 + 3𝑥2 + 6𝑥3 = 24
3𝑥1 + 6𝑥2 − 9𝑥3 = −3
9𝑥1 − 21𝑥2 + 12𝑥3 = 30

c. Find the values of 𝜆 for which the determinant of the matrix below is equal to zero. (5 marks)
𝜆+1 0 0
[ 4 𝜆 3 ]
2 8 𝜆+5

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d. Let
1 2 −2
𝐴 = [2 −3 10 ]
0 1 −3
Find the ad joint of 𝐴 and hence find 𝐴−1 (8 marks)

e. i. ) State the Cramer’s rule (2 marks)


ii.) Use Gaussian elimination to solve the following systems of linear equations. (6 marks)
𝑥1 + 2𝑥2 + 3𝑥3 = 9
−𝑥1 + 3𝑥2 = −4
2𝑥1 − 5𝑥2 + 5𝑥3 = 17

QUESTION TWO (20 MARKS)


a. i. ) Define the term symmetric matrix. (1 mark)

ii. ) Prove that a symmetric matrix of order 2 is diagonalizable. (4 marks)

iii.) State the Cayley – Hamilton’s theorem and use it to verify for the matrix. (4 marks)

1 −3
𝐴=[ ]
2 5

b. Show that the determinant of a second order matrix with identical rows is zero. (2 marks)

2 −1 1 −4
c. Consider the matrices 𝐴 = [ ],𝐵=[ ] determine whether these matrices
4 3 4 −1
commute and hence find the commutator . (4 marks)

d. Use Cramer’s rule to find the point of intersection of the three planes defined by: (5 marks)

𝑥 + 2𝑦 − 𝑧 = 4
2𝑥 − 2𝑦 + 3𝑧 = 3
4𝑥 + 3𝑦 − 2𝑧 = 5
QUESTION THREE (20 MARKS)

a. Apply the Gram-Schmidt process to construct an orthogonal basis set for (7 marks)
𝐵 = {(1,1,0), (1,2,0), (0,1,2)} 𝑜𝑓 ℝ3

b. Show that the transformation 𝑇(𝑥) = 2𝑥 + 1 is not a linear transformation. (3 marks)

5 2
c. Find the Eigen values of the matrix 𝐴 = [ ] (5 marks)
9 2

1 2
d. Let 𝐴 = [ ] Determine whether or not A is diagnosable. (5 marks)
0 1

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QUESTION FOUR (20 MARKS)

a. Calculate the area of the triangle whose vertices are 𝐴(1,0), 𝐵(2,2)𝑎𝑛𝑑 𝐶(4,3) by use of the
method of determinants. (4 marks)

b. Consider the vectors 𝑢 = (1, −3,7)𝑎𝑛𝑑 𝑣 = (8, −2, −2) Find 𝑢, 𝑣 and the angle between them

(5mks)
c. i. ) Let 𝑉 = ℝ3 with standard operations and 𝑆 = {(1,2,3), (0,1,2), (−2,0,1)} ≤ ℝ3
Does 𝑆Span 𝑉?

ii. ) Let 𝑉 = ℝ3 and 𝑆 = {(−4, −3,4), (1, −2,3), (6,0,0)} determine whether 𝑆 is linearly
independent (4 marks)

d. Find the rank of the matrix below (4 marks)

1 −2 3
𝐴 [2 −5 1]
1 −4 −7

QUESTION FIVE (20 MARKS)

a. i. ) Define the term Basis of a vector space 𝑉 (2 marks)

ii. ) Let 𝑆 = {𝑉1 = (1,2,1), 𝑉2 = (2,9,0), 𝑎𝑛𝑑 𝑉3 = (3,3,4)} (3 marks)


Show that the set 𝑆 is basis for ℝ3

b. Show that < 𝑢, 𝑣 >= 𝑢1 𝑣1 − 2𝑢2 𝑣2 𝑤ℎ𝑒𝑟𝑒 𝑢 = (𝑢1 𝑢2 ) 𝑣 = (𝑣1 𝑣2 ) is an inner product on ℝ2
(5mks)

c. i. ) Define the term Linear transformation. (1 mark)


𝑥1
𝑥 +𝑥
ii. ) Show that 𝑇: ℝ3 → ℝ2 defined by 𝑇 = [𝑥2 ] = [𝑥1 − 𝑥2 ] is a linear transformation (6 marks)
𝑥3 2 1

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