Core arithmetic modules, quantitative aptitude exercises, algebraic reasoning, and analytical geometry tracking systems.
1. Set Theory & Boolean Logic
1.1 Basic Concepts
- Set: A well-defined collection of distinct objects.
- Elements: Members of a set (denoted by
∈). - Empty Set (∅ or {}): Set with no elements.
- Universal Set (U): Set of all elements under consideration.
- Cardinality (n(A)): Number of elements in set A.
1.2 Set Operations
OperationSymbolDefinitionExampleUnionA ∪ B{x: x∈A or x∈B}{1,2} ∪ {2,3} = {1,2,3}IntersectionA ∩ B{x: x∈A and x∈B}{1,2} ∩ {2,3} = {2}DifferenceA – B or A\B{x: x∈A and x∉B}{1,2} – {2,3} = {1}ComplementA' or A<sup>c</sup>{x∈U: x∉A}If U={1,2,3}, A={2} → A'={1,3}Symmetric DifferenceA Δ B(A–B) ∪ (B–A){1,2} Δ {2,3} = {1,3}
1.3 Power Set
- Power Set P(A): Set of all subsets of A.
|P(A)| = 2^nwheren = |A|- Example: A = {a,b} → P(A) = {∅, {a}, {b}, {a,b}}
1.4 Set-Builder Notation
{x ∈ ℕ : x < 5}means {1,2,3,4}{x² : x ∈ ℤ, -2 ≤ x ≤ 2}means {0,1,4}
1.5 De-Morgan's Laws (Critical for Exam)
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(A ∪ B)' = A' ∩ B' (A ∩ B)' = A' ∪ B'
1.6 Boolean Logic
- Logical operators: AND (∧), OR (∨), NOT (¬), Implies (→), If and only if (↔)
- Truth tables for basic gates
- Logical equivalence: De-Morgan in logic:
¬(P ∧ Q) = ¬P ∨ ¬Q
<aside> 📌 **Sample Question:**
Q: If A = {1,2,3,4}, B = {3,4,5,6}, then A Δ B is:
(a) {1,2,5,6} (b) {3,4} (c) {1,2,3,4,5,6} (d) ∅
Answer: (a) {1,2,5,6}
Explanation: A Δ B = (A–B) ∪ (B–A) = {1,2} ∪ {5,6} = {1,2,5,6}
</aside>2. Calculus
2.1 Limits
- Definition:
lim(x→a) f(x) = Lmeans f(x) approaches L as x approaches a. - Indeterminate forms: 0/0, ∞/∞, ∞–∞, 0×∞, 1^∞, 0^0, ∞^0
Important Limit Formulas
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lim(x→0) sin x / x = 1 lim(x→0) (1 – cos x)/x = 0 lim(x→0) tan x / x = 1 lim(x→0) (e^x – 1)/x = 1 lim(x→0) ln(1+x)/x = 1 lim(x→∞) (1 + 1/x)^x = e
Methods to Solve Limits
- Direct substitution – if no indeterminate form
- Factorization – cancel common factors
- Rationalization – multiply by conjugate
- L'Hôpital's Rule – differentiate numerator and denominator
<aside> 📌 **Example:** `lim(x→2) (x² – 4)/(x – 2) = lim(x→2) (x–2)(x+2)/(x–2) = lim(x→2) (x+2) = 4` </aside>
2.2 Continuity
A function f(x) is continuous at x = a if:
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1. f(a) is defined 2. lim(x→a) f(x) exists 3. lim(x→a) f(x) = f(a)
- Types of discontinuity: Removable, Jump, Infinite
2.3 Differentiation (Derivatives)
Basic Derivatives
f(x)f'(x)c (constant)0x^nn·x^(n–1)e^xe^xln x1/xsin xcos xcos x–sin xtan xsec² xsec xsec x·tan xcot x–csc² xcsc x–csc x·cot x
Rules of Differentiation
- Sum/Difference: (u ± v)' = u' ± v'
- Product Rule: (uv)' = u'v + uv'
- Quotient Rule: (u/v)' = (u'v – uv')/v²
- Chain Rule: f(g(x))' = f'(g(x))·g'(x)
<aside> 📌 **Example:** Find derivative of `sin(x²)` **Solution:** `d/dx sin(x²) = cos(x²) · 2x = 2x·cos(x²)` </aside>
2.4 Integration
Basic Integrals
∫f(x) dxResult∫x^n dxx^(n+1)/(n+1) + C, n≠–1∫1/x dxlnx+ C∫e^x dxe^x + C∫sin x dx–cos x + C∫cos x dxsin x + C∫sec² x dxtan x + C
Definite Integral
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∫_a^b f(x) dx = F(b) – F(a)
where F is the antiderivative of f.
<aside> 📌 **Example:** ∫_0^1 x² dx = [x³/3]_0^1 = 1/3 – 0 = 1/3 </aside>3. Algebra & Matrices
3.1 Number Systems
SetSymbolDescriptionNaturalℕ{1,2,3,…}Whole𝕎{0,1,2,3,…}Integersℤ{…,-2,-1,0,1,2,…}Rationalℚp/q, q≠0Irrationalℚ'√2, π, eRealℝℚ ∪ ℚ'Complexℂa + bi
3.2 Inequalities
- Linear:
ax + b > 0→x > –b/a(reverse sign if multiplying/dividing by negative) - Quadratic: Solve as equation, then test intervals
- Absolute value:
|x| < a→–a < x < a;|x| > a→x < –a or x > a
<aside> 📌 **Example:** Solve `x² – 5x + 6 > 0` → (x–2)(x–3) > 0 → x < 2 or x > 3 </aside>
3.3 Domain of a Function
- Denominator ≠ 0
- Inside square root ≥ 0
- Inside logarithm > 0
<aside> 📌 **Example:** Domain of `f(x) = √(x–3)/(x²–4)` **Solution:** x–3 ≥ 0 → x ≥ 3; and x²–4 ≠ 0 → x ≠ ±2. Domain = [3, ∞) </aside>
3.4 Binomial Expansion
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(a + b)^n = Σ_{k=0}^n C(n,k) a^(n–k) b^k
where C(n,k) = n!/(k!(n–k)!)
- General term:
T_(k+1) = C(n,k) a^(n–k) b^k
<aside> 📌 **Example:** 3rd term of (x + 2)^5: T_3 = C(5,2) x³·2² = 10·x³·4 = 40x³ </aside>
3.5 Matrices
Basic Definitions
- Order: m × n (rows × columns)
- Square matrix: m = n
- Symmetric: A = A^T (a_ij = a_ji)
- Skew-symmetric: A^T = –A (a_ij = –a_ji, diagonal = 0)
Determinant
- For 2×2:
det[[a,b],[c,d]] = ad – bc - For 3×3: Use Sarrus rule or cofactor expansion
Matrix Operations
- Addition/Subtraction: Same order only
- Multiplication: (m×n) × (n×p) → (m×p); not commutative (AB ≠ BA generally)
<aside> 📌 **Sample Question:**
Q: If A = [[1,2],[3,4]], then |A| = ?
(a) –2 (b) 2 (c) 10 (d) –10
Answer: (a) –2
Explanation: |A| = (1×4) – (2×3) = 4 – 6 = –2
</aside>4. Coordinate Geometry
4.1 Distance and Midpoint
- Distance between (x₁,y₁) and (x₂,y₂):
d = √[(x₂–x₁)² + (y₂–y₁)²] - Midpoint:
M = ((x₁+x₂)/2, (y₁+y₂)/2)
4.2 Equation of a Straight Line
FormEquationKey infoSlope-intercepty = mx + cm = slope, c = y-interceptPoint-slopey – y₁ = m(x – x₁)passes through (x₁,y₁)Two-point(y–y₁)/(y₂–y₁) = (x–x₁)/(x₂–x₁)passes through two pointsInterceptx/a + y/b = 1a = x-intercept, b = y-interceptGeneralAx + By + C = 0slope = –A/B
- Parallel lines: m₁ = m₂
- Perpendicular lines: m₁·m₂ = –1
4.3 Conic Sections
Circle
- Center (h,k), radius r:
(x–h)² + (y–k)² = r² - General form:
x² + y² + 2gx + 2fy + c = 0, center = (–g,–f), radius = √(g²+f²–c)
Parabola (Standard forms)
OrientationEquationFocusDirectrixRighty² = 4ax(a,0)x = –aLefty² = –4ax(–a,0)x = aUpx² = 4ay(0,a)y = –aDownx² = –4ay(0,–a)y = a
Ellipse
- Horizontal major axis:
x²/a² + y²/b² = 1(a > b) - Foci: (±c,0) where c² = a² – b²
Hyperbola
- Horizontal transverse axis:
x²/a² – y²/b² = 1 - Foci: (±c,0) where c² = a² + b²
4.4 Equation of Tangent
- To circle x² + y² = r² at (x₁,y₁):
xx₁ + yy₁ = r² - To parabola y² = 4ax at (x₁,y₁):
yy₁ = 2a(x + x₁)
5. Vectors & 3D Geometry
5.1 Basic Vector Operations
- Representation:
\vec{a} = a₁\hat{i} + a₂\hat{j} + a₃\hat{k} - Magnitude:
|\vec{a}| = √(a₁² + a₂² + a₃²)
5.2 Dot Product (Scalar Product)
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\vec{a}·\vec{b} = |\vec{a}||\vec{b}|cosθ = a₁b₁ + a₂b₂ + a₃b₃
- Perpendicular:
\vec{a}·\vec{b} = 0 - Projection of
\vec{a}on\vec{b}=(\vec{a}·\vec{b})/|\vec{b}|
5.3 Cross Product (Vector Product)
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\vec{a} × \vec{b} = |\vec{a}||\vec{b}|sinθ · \hat{n}
Determinant form:
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\vec{a} × \vec{b} = det[ [\hat{i}, \hat{j}, \hat{k}],
[a₁, a₂, a₃],
[b₁, b₂, b₃] ]
- Parallel:
\vec{a} × \vec{b} = 0 - Magnitude = area of parallelogram
5.4 Direction Cosines
For a vector making angles α, β, γ with axes:
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l = cosα, m = cosβ, n = cosγ l² + m² + n² = 1
- Direction ratios: a, b, c proportional to l, m, n
5.5 Lines in 3D
- Symmetric form:
(x–x₁)/a = (y–y₁)/b = (z–z₁)/c - Parallel lines: direction ratios proportional
- Perpendicular lines: dot product of direction vectors = 0
6. Statistics & Probability
6.1 Measures of Central Tendency
Arithmetic Mean (AM)
- Ungrouped:
AM = (Σx)/n - Grouped:
AM = (Σfx)/Σf
Geometric Mean (GM)
GM = (x₁·x₂·...·x_n)^(1/n)- For two numbers a and b:
GM = √(ab)
Harmonic Mean (HM)
HM = n / (Σ(1/x))- For two numbers a and b:
HM = 2ab/(a+b)
Relationship between AM, GM, HM (Important)
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AM ≥ GM ≥ HM Equality holds when all numbers are equal.
Also: GM² = AM × HM
6.2 Correlation
- Range of correlation coefficient (r):
–1 ≤ r ≤ 1 - r = +1 → perfect positive correlation
- r = –1 → perfect negative correlation
- r = 0 → no linear correlation
6.3 Population vs Sample
ParameterPopulationSampleMeanμ (mu)x̄ (x-bar)Standard deviationσ (sigma)sVarianceσ²s²SizeNn
6.4 Probability
Basic Definitions
- Experiment: Process with uncertain outcome
- Sample space (S) : All possible outcomes
- Event (E) : Subset of S
- Probability:
P(E) = n(E)/n(S)(equally likely outcomes)
Mutually Exclusive Events
- Events that cannot occur simultaneously:
P(A ∩ B) = 0 - Addition rule:
P(A ∪ B) = P(A) + P(B)
Conditional Probability
P(A|B) = P(A ∩ B)/P(B)- Independent events:
P(A ∩ B) = P(A)·P(B)
<aside> 📌 **Sample Question:**
Q: Two dice are rolled. Probability of sum 7 is:
(a) 1/6 (b) 1/12 (c) 1/36 (d) 5/36
Answer: (a) 1/6
Explanation: Pairs: (1,6),(2,5),(3,4),(4,3),(5,2),(6,1) → 6/36 = 1/6
</aside>7. Complex Numbers & Group Theory
7.1 Complex Numbers
- Standard form:
z = a + bi, where i² = –1 - Real part: Re(z) = a
- Imaginary part: Im(z) = b
- Complex conjugate:
\bar{z} = a – bi
7.2 Powers of i (Imaginary Unit)
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i¹ = i i² = –1 i³ = –i i⁴ = 1
Cycle repeats every 4: i^(4k) = 1, i^(4k+1) = i, i^(4k+2) = –1, i^(4k+3) = –i
<aside> 📌 **Example:** i^(99) = i^(96+3) = i^96 × i³ = (i⁴)^24 × (–i) = 1 × (–i) = –i </aside>
7.3 Operations on Complex Numbers
- Addition: (a+bi)+(c+di) = (a+c)+(b+d)i
- Multiplication: (a+bi)(c+di) = (ac–bd)+(ad+bc)i
- Division: Multiply numerator and denominator by conjugate
7.4 Modulus and Argument
- Modulus:
|z| = √(a² + b²) - Argument:
θ = tan⁻¹(b/a)(consider quadrant)
7.5 Group Theory (Basic for Entrance)
Definition of a Group
A set G with operation * is a group if:
- Closure: a*b ∈ G for all a,b∈G
- Associativity: (ab)c = a(bc)
- Identity: ∃ e∈G such that ae = ea = a
- Inverse: For each a∈G, ∃ a⁻¹∈G such that aa⁻¹ = a⁻¹a = e
Abelian Group
A group where operation is commutative: a*b = b*a for all a,b∈G
Examples
- (ℤ, +) is an Abelian group
- (ℚ{0}, ×) is an Abelian group
- 2×2 matrices under multiplication: not Abelian generally
<aside> 📌 **Sample Question:**
Q: Which of the following is NOT an Abelian group?
(a) (ℤ, +) (b) (ℝ, +) (c) 2×2 matrices under multiplication (d) (ℂ, +)
Answer: (c) 2×2 matrices under multiplication (not commutative)
</aside>✅ Formula Summary Table (Quick Revision)
TopicKey FormulaSetn(A∪B) = n(A) + n(B) – n(A∩B)Limitlim(x→0) sin x/x = 1Derivatived/dx(x^n) = n x^(n–1)Integral∫x^n dx = x^(n+1)/(n+1) + CMatrixdet[[a,b],[c,d]] = ad – bcLinem = (y₂–y₁)/(x₂–x₁)Circle(x–h)² + (y–k)² = r²Vectora·b =abcosθAM, GM, HMGM² = AM × HMProbabilityP(E) = n(E)/n(S)Complexi² = –1
📝 10 Quick Practice Questions (with Answers)
- Set: If A = {2,4,6}, B = {4,6,8}, then A – B = ? → {2}
- Limit: lim(x→0) sin(3x)/x = ? → 3
- Derivative: d/dx(cos x²) = ? → –2x·sin(x²)
- Integration: ∫(2x) dx = ? → x² + C
- Matrix: Determinant of [[3,4],[2,5]] = ? → (3×5 – 4×2) = 15 – 8 = 7
- Coordinate: Slope of line through (1,2) and (4,8) = ? → (8–2)/(4–1) = 6/3 = 2
- Vector: If a·b = 0, vectors are? → Perpendicular
- Statistics: If AM=10, GM=8, then HM = ? → GM² = AM×HM → 64 = 10×HM → HM = 6.4
- Probability: Probability of getting head on a fair coin = ? → 1/2
- Complex: i^(50) = ? → (i⁴)^12 × i² = 1 × (–1) = –1