I've analyzed all your exam papers from Om Sterling Global University - Remedial Mathematics (DPH-106). Below is a complete Question Bank with Full Solutions covering all important chapters - designed to be studied in one day!
π REMEDIAL MATHEMATICS - QUESTION BANK WITH SOLUTIONS
(Based on Your Actual Exam Papers - DPH-106)
CHAPTER 1: MATRICES AND DETERMINANTS
Q1. Define Matrix and its Order.
Answer:
A Matrix is a rectangular arrangement of numbers (real or complex) arranged in rows and columns, enclosed in brackets.
Order of a matrix = Number of rows Γ Number of columns
Example:
A = [1 2 3]
[4 5 6]
This matrix has 2 rows and 3 columns, so its order is 2Γ3.
Q2. Add a Note on Types of Matrices.
Answer:
| Type | Description | Example |
|---|
| Row Matrix | Only 1 row | [1, 2, 3] |
| Column Matrix | Only 1 column | [1; 2; 3] |
| Square Matrix | Rows = Columns | 2Γ2, 3Γ3 |
| Zero Matrix | All elements = 0 | [0,0;0,0] |
| Identity Matrix (I) | Diagonal = 1, rest = 0 | [1,0;0,1] |
| Diagonal Matrix | Non-diagonal = 0 | [2,0;0,5] |
| Symmetric Matrix | A = A^T | - |
| Skew-Symmetric | A = -A^T | - |
Q3. State Transpose of a Matrix with Example.
Answer:
The Transpose of matrix A (written as A^T) is obtained by interchanging rows and columns.
Example:
If A = [1 2 3] Then A^T = [1 4]
[4 5 6] [2 5]
[3 6]
Property: (A^T)^T = A
Q4. Write a Note on Operations on Matrices with Example.
Answer:
1. Addition: Add corresponding elements. (Same order required)
[1 2] + [5 6] = [6 8]
[3 4] [7 8] [10 12]
2. Subtraction: Subtract corresponding elements.
3. Scalar Multiplication:
2 Γ [1 2] = [2 4]
[3 4] [6 8]
4. Matrix Multiplication: (A is mΓn, B is nΓp β AB is mΓp)
[1 2] Γ [5 6] = [(1Γ5+2Γ7) (1Γ6+2Γ8)] = [19 22]
[3 4] [7 8] [(3Γ5+4Γ7) (3Γ6+4Γ8)] [43 50]
Q5. Find Adj(A) and Aβ»ΒΉ for the matrix:
A = [1 1 1]
[1 2 -3]
[2 -1 3]
Step 1 - Find det(A):
det(A) = 1(2Γ3 - (-3)Γ(-1)) - 1(1Γ3 - (-3)Γ2) + 1(1Γ(-1) - 2Γ2)
= 1(6 - 3) - 1(3 + 6) + 1(-1 - 4)
= 1(3) - 1(9) + 1(-5)
= 3 - 9 - 5 = -11
Step 2 - Find Cofactor Matrix:
Cββ = +(2Γ3 - (-3)Γ(-1)) = +(6-3) = 3
Cββ = -(1Γ3 - (-3)Γ2) = -(3+6) = -9
Cββ = +(1Γ(-1) - 2Γ2) = +(-1-4) = -5
Cββ = -(1Γ3 - 1Γ(-1)) = -(3+1) = -4
Cββ = +(1Γ3 - 1Γ2) = +(3-2) = 1
Cββ = -(1Γ(-1) - 1Γ2) = -(-1-2) = 3
Cββ = +(1Γ(-3) - 1Γ2) = +(-3-2) = -5
Cββ = -(1Γ(-3) - 1Γ1) = -(-3-1) = 4
Cββ = +(1Γ2 - 1Γ1) = +(2-1) = 1
Cofactor Matrix:
C = [ 3 -9 -5]
[-4 1 3]
[-5 4 1]
Step 3 - Adj(A) = Transpose of Cofactor Matrix:
Adj(A) = [ 3 -4 -5]
[-9 1 4]
[-5 3 1]
Step 4 - Aβ»ΒΉ = Adj(A) / det(A):
Aβ»ΒΉ = (1/-11) Γ [ 3 -4 -5]
[-9 1 4]
[-5 3 1]
Aβ»ΒΉ = [-3/11 4/11 5/11]
[ 9/11 -1/11 -4/11]
[ 5/11 -3/11 -1/11]
Q6. Find Adjoint of Matrix:
A = [ 1 3 4]
[-1 6 0]
[ 3 4 2]
det(A) = 1(12-0) - 3(-2-0) + 4(-4-18)
= 12 + 6 - 88 = -70
Cofactors:
Cββ = +(12-0) = 12
Cββ = -(-2-0) = 2
Cββ = +(-4-18) = -22
Cββ = -(6-16) = 10
Cββ = +(2-12) = -10
Cββ = -(4-9) = 5
Cββ = +(0-24) = -24
Cββ = -(0+4) = -4
Cββ = +(6+3) = 9
Adj(A):
Adj(A) = [ 12 10 -24]
[ 2 -10 -4]
[-22 5 9]
Q7. Solve by Cramer's Rule: 5x - 7y + z = 11, 6x - 8y - z = 15, 3x + 2y - 6z = 7
Setting up:
D = |5 -7 1|
|6 -8 -1|
|3 2 -6|
D = 5[(-8)(-6)-(-1)(2)] - (-7)[(6)(-6)-(-1)(3)] + 1[(6)(2)-(-8)(3)]
= 5[48+2] + 7[-36+3] + 1[12+24]
= 5(50) + 7(-33) + 1(36)
= 250 - 231 + 36 = 55
Dx = |11 -7 1|
|15 -8 -1|
| 7 2 -6|
Dx = 11[48+2] - (-7)[(-90+7)] + 1[30+56]
= 11(50) + 7(-83) + 86
= 550 - 581 + 86 = 55
Dy = |5 11 1|
|6 15 -1|
|3 7 -6|
Dy = 5[(-90+7)] - 11[(-36+3)] + 1[(42-45)]
= 5(-83) - 11(-33) + (-3)
= -415 + 363 - 3 = -55
Dz = |5 -7 11|
|6 -8 15|
|3 2 7|
Dz = 5(-56-30) - (-7)(42-45) + 11(12+24)
= 5(-86) + 7(-3) + 11(36)
= -430 - 21 + 396 = -55
Solutions:
- x = Dx/D = 55/55 = 1
- y = Dy/D = -55/55 = -1
- z = Dz/D = -55/55 = -1
Q8. Solve by Matrix Method: x+y+z=3, 2x-y+z=2, x-2y+3z=2
Matrix form AX = B:
A = [1 1 1] X = [x] B = [3]
[2 -1 1] [y] [2]
[1 -2 3] [z] [2]
det(A) = 1(-3+2) - 1(6-1) + 1(-4+1)
= -1 - 5 - 3 = -9 ... wait, let me recalculate:
= 1((-1)(3)-(1)(-2)) - 1((2)(3)-(1)(1)) + 1((2)(-2)-(-1)(1))
= 1(-3+2) - 1(6-1) + 1(-4+1)
= 1(-1) - 1(5) + 1(-3) = -9
Using Cramer's rule:
Dx: Replace col 1 with B:
|3 1 1|
|2 -1 1| = 3(-3+2)-1(6-2)+1(-4+2) = 3(-1)-1(4)+1(-2) = -3-4-2 = -9
|2 -2 3|
x = -9/-9 = 1
Dy: Replace col 2 with B:
|1 3 1|
|2 2 1| = 1(6-2)-3(6-1)+1(-4-2) = 4-15-6 = -17
|1 2 3|
Hmm, let me redo: = 1(2Γ3-1Γ2)-3(2Γ3-1Γ1)+1(2Γ2-2Γ1)
= 1(4) - 3(5) + 1(2) = 4-15+2 = -9
y = -9/-9 = 1
Dz: Replace col 3 with B:
|1 1 3|
|2 -1 2| = 1(-2+4)-1(4-2)+3(-4+1) = 2-2-9 = -9
|1 -2 2|
z = -9/-9 = 1
Answer: x = 1, y = 1, z = 1
Q9. Resolve (x-5)/[(x-3)(x-4)] into Partial Fractions
Let: (x-5)/[(x-3)(x-4)] = A/(x-3) + B/(x-4)
Multiply both sides by (x-3)(x-4):
x - 5 = A(x-4) + B(x-3)
Put x = 3: 3-5 = A(3-4) β -2 = -A β A = 2
Put x = 4: 4-5 = B(4-3) β -1 = B β B = -1
Answer: (x-5)/[(x-3)(x-4)] = 2/(x-3) - 1/(x-4)
CHAPTER 2: ANALYTICAL GEOMETRY
Q10. Define Quadrant.
Answer:
The coordinate axes divide the plane into 4 regions called Quadrants:
| Quadrant | x | y | Example |
|---|
| I (First) | + | + | (3, 5) |
| II (Second) | - | + | (-2, 4) |
| III (Third) | - | - | (-1, -3) |
| IV (Fourth) | + | - | (4, -2) |
Q11. Define Distance Formula.
Answer:
The distance between two points P(xβ, yβ) and Q(xβ, yβ) is:
d = β[(xβ-xβ)Β² + (yβ-yβ)Β²]
This is derived from the Pythagorean theorem.
Q12. Find the Distance between (5, 4) and (-5, 6).
Solution:
d = β[(-5-5)Β² + (6-4)Β²]
= β[(-10)Β² + (2)Β²]
= β[100 + 4]
= β104
= 2β26 β 10.2 units
Q13. Show the four points (0,5), (-2,-2), (5,0) and (7,7) on a graph.
Answer:
Plot each point on the coordinate plane:
- (0,5) - on Y-axis, 5 units up
- (-2,-2) - 2nd quadrant (negative both)... wait, (-2,-2) is in 3rd quadrant
- (5,0) - on X-axis, 5 units right
- (7,7) - 1st quadrant
Y
8| *(7,7)
7|
6|
5| *(0,5)
4|
3|
2|
1|
--+--+--+--+--+--+--+-- X
-3 -2 -1 0 1 2 3 4 5 6 7
*(5,0)
-1|
-2| *(-2,-2)
These 4 points form a quadrilateral when joined.
Q14. Find Area of Triangle with vertices (0,0), (1,0), (1,1).
Formula:
Area = (1/2)|xβ(yβ-yβ) + xβ(yβ-yβ) + xβ(yβ-yβ)|
= (1/2)|0(0-1) + 1(1-0) + 1(0-0)|
= (1/2)|0 + 1 + 0|
= (1/2)|1|
= 1/2 square unit
Q15. Find the equation of a straight line passing through (-4, -2) with slope -8.
Using Point-Slope Form: y - yβ = m(x - xβ)
y - (-2) = -8(x - (-4))
y + 2 = -8(x + 4)
y + 2 = -8x - 32
y = -8x - 34 or 8x + y + 34 = 0
CHAPTER 3: TRIGONOMETRY
Q16. Prove: cos 52Β° = cos 68Β° + cos 172Β° = 0
Proof:
cos 68Β° + cos 172Β°
Using sum-to-product: cos A + cos B = 2cos[(A+B)/2]cos[(A-B)/2]
= 2cos[(68+172)/2]cos[(172-68)/2]
= 2cos(120Β°)cos(52Β°)
= 2(-1/2)cos(52Β°)
= -cos(52Β°)
So: cos 68Β° + cos 172Β° = -cos 52Β°
Therefore: cos 52Β° + cos 68Β° + cos 172Β° = cos 52Β° - cos 52Β° = 0 β
Q17. If tan A = β3 and tan B = 2-β3, find tan(A-B).
Formula: tan(A-B) = (tan A - tan B)/(1 + tan A Β· tan B)
tan A - tan B = β3 - (2-β3) = β3 - 2 + β3 = 2β3 - 2
tan A Β· tan B = β3(2-β3) = 2β3 - 3
1 + tan A Β· tan B = 1 + 2β3 - 3 = 2β3 - 2
tan(A-B) = (2β3-2)/(2β3-2) = 1
Therefore: A - B = 45Β°
CHAPTER 4: DIFFERENTIAL CALCULUS
Q18. Differentiate y = log(x) Β· tan(x) with respect to x.
Using Product Rule: d/dx[uΒ·v] = uΒ·v' + vΒ·u'
Let u = log x β du/dx = 1/x
Let v = tan x β dv/dx = secΒ²x
dy/dx = log(x) Β· secΒ²x + tan(x) Β· (1/x)
dy/dx = log(x)Β·secΒ²x + tan(x)/x
Q19. If y = xβΈ - 12xβ΅ + 5xΒ³ - 12, find dΒ²y/dxΒ².
First derivative:
dy/dx = 8xβ· - 60xβ΄ + 15xΒ²
Second derivative:
dΒ²y/dxΒ² = 56xβΆ - 240xΒ³ + 30x
Q20. Find dy/dx if y = 3xΒ² + 7xβ· and y = xβ΄ + sin x.
Part (a): y = 3xΒ² + 7xβ·
dy/dx = 6x + 49xβΆ
Part (b): y = xβ΄ + sin x
dy/dx = 4xΒ³ + cos x
CHAPTER 5: DIFFERENTIAL EQUATIONS
Q21. Add a Note on Differential Equation.
Answer:
A Differential Equation is an equation that contains derivatives of a dependent variable with respect to one or more independent variables.
Examples:
- dy/dx = 2x + 3 (1st order)
- dΒ²y/dxΒ² + 5(dy/dx) + 6y = 0 (2nd order)
- 2xydx + (xΒ²+yΒ²)dy = 0
Types:
- Ordinary DE (ODE): One independent variable
- Partial DE (PDE): Two or more independent variables
Q22. Define Order and Degree of a Differential Equation with 3 Examples.
Definitions:
- Order = the order of the highest derivative present
- Degree = the power of the highest order derivative (after clearing fractions/radicals)
| Equation | Order | Degree |
|---|
| dy/dx = 5x + 3 | 1 | 1 |
| (dΒ²y/dxΒ²)Β³ + dy/dx = 0 | 2 | 3 |
| dΒ³y/dxΒ³ + 2(dy/dx)Β² = x | 3 | 1 |
Q23. Solve the Differential Equation: 2xyΒ·dx + (xΒ² + yΒ²)dy = 0
Rearranging:
2xyΒ·dx = -(xΒ²+yΒ²)dy
dx/dy = -(xΒ²+yΒ²)/(2xy)
This is a homogeneous equation. Let x = vy β dx/dy = v + yΒ·dv/dy
v + yΒ·dv/dy = -(vΒ²yΒ²+yΒ²)/(2vyΒ²) = -(vΒ²+1)/(2v)
yΒ·dv/dy = -(vΒ²+1)/(2v) - v = -(vΒ²+1+2vΒ²)/(2v) = -(3vΒ²+1)/(2v)
Separating variables:
2vΒ·dv/(3vΒ²+1) = -dy/y
Integrating both sides:
(1/3)ln(3vΒ²+1) = -ln y + C
ln(3vΒ²+1) = -3ln y + C
(3vΒ²+1) = k/yΒ³
Substituting back v = x/y:
(3xΒ²/yΒ² + 1) = k/yΒ³
3xΒ² + yΒ² = ky β General Solution
Q24. Solve: 4dΒ²y/dxΒ² + 4dy/dx - 3y = e^(2x)
Auxiliary Equation: 4mΒ² + 4m - 3 = 0
(2m+3)(2m-1) = 0
m = 1/2 or m = -3/2
Complementary Function (C.F.):
y_c = Cβe^(x/2) + Cβe^(-3x/2)
Particular Integral (P.I.): For e^(2x):
P.I. = e^(2x)/f(D) where Dβ2
= e^(2x)/(4(4)+4(2)-3) = e^(2x)/(16+8-3) = e^(2x)/21
General Solution:
y = Cβe^(x/2) + Cβe^(-3x/2) + e^(2x)/21
CHAPTER 6: INTEGRAL CALCULUS
Q25. Evaluate β«(3xΒ² + 2x + 5)dx
= 3xΒ³/3 + 2xΒ²/2 + 5x + C
= xΒ³ + xΒ² + 5x + C
Q26. Evaluate β«sin(x)dx and β«cos(x)dx
β«sin(x)dx = -cos(x) + C
β«cos(x)dx = sin(x) + C
Q27. Evaluate β«e^x dx and β«(1/x)dx
β«e^x dx = e^x + C
β«(1/x)dx = ln|x| + C
CHAPTER 7: LAPLACE TRANSFORM
Q28. Define Laplace Transform.
Answer:
The Laplace Transform of a function f(t) is defined as:
L{f(t)} = F(s) = β«β^β e^(-st) f(t) dt
where s is a complex number.
Q29. Standard Laplace Transform Formulas (Must Memorize):
| f(t) | L{f(t)} = F(s) |
|---|
| 1 | 1/s |
| t | 1/sΒ² |
| tβΏ | n!/s^(n+1) |
| e^(at) | 1/(s-a) |
| sin(at) | a/(sΒ²+aΒ²) |
| cos(at) | s/(sΒ²+aΒ²) |
| e^(at)sin(bt) | b/[(s-a)Β²+bΒ²] |
| e^(at)cos(bt) | (s-a)/[(s-a)Β²+bΒ²] |
Q30. Find L{3tΒ² + 2e^(3t) + sin 4t}
L{3tΒ²} = 3 Γ 2!/sΒ³ = 6/sΒ³
L{2e^(3t)} = 2/(s-3)
L{sin 4t} = 4/(sΒ²+16)
Answer: L = 6/sΒ³ + 2/(s-3) + 4/(sΒ²+16)
QUICK REVISION SUMMARY TABLE
| Chapter | Key Topics to Remember |
|---|
| Matrices | Order, Types, Adj, Aβ»ΒΉ, Cramer's Rule |
| Analytical Geometry | Distance formula, Area of triangle, Line equation, Quadrants |
| Trigonometry | Sum-to-product, tan(A-B) formula |
| Differential Calculus | Product rule, Chain rule, 2nd derivatives |
| Differential Equations | Order, Degree, Homogeneous, 2nd order linear |
| Integral Calculus | Standard integrals, Definite integrals |
| Laplace Transform | Definition, Standard formulas |
Study Tip: Focus on Q5-Q8 (Matrices), Q12-Q15 (Geometry), and Q23-Q24 (DEs) as they appear most frequently in your past papers. Good luck! π―