💡 Exam Scoring Secret: In CBSE Mathematics, formula application accounts for up to 40% of step-marking. Always write the general formula clearly at the top of your solution before substituting numerical values.
🔢 1. Number Systems & Polynomials
A. Real Numbers:
- Fundamental Theorem of Arithmetic: Every composite number can be uniquely expressed (factorised) as a product of primes, apart from the order in which prime factors occur.
- HCF and LCM Relation: For any two positive integers
aandb:
HCF(a, b) × LCM(a, b) = a × b - Irrationality: If
pis a prime number andpdividesa², thenpdividesa(whereais a positive integer). Used to prove √2, √3, and √5 are irrational.
B. Polynomials:
- For quadratic polynomial
P(x) = ax² + bx + cwith zerosαandβ:
• Sum of zeros:α + β = -b / a
• Product of zeros:α · β = c / a - Forming quadratic polynomial:
k · [x² - (Sum of zeros)x + (Product of zeros)] = k · [x² - (α + β)x + αβ].
⚖️ 2. Algebra: Linear & Quadratic Equations
A. Pair of Linear Equations in Two Variables:
For system a₁x + b₁y + c₁ = 0 and a₂x + b₂y + c₂ = 0:
- Unique Solution (Consistent & Intersecting Lines):
a₁/a₂ ≠ b₁/b₂. - Infinitely Many Solutions (Consistent & Coincident Lines):
a₁/a₂ = b₁/b₂ = c₁/c₂. - No Solution (Inconsistent & Parallel Lines):
a₁/a₂ = b₁/b₂ ≠ c₁/c₂.
B. Quadratic Equations:
Standard form: ax² + bx + c = 0 (where a ≠ 0).
- Quadratic Formula (Sridharacharya's Rule):
x = (-b ± √(b² - 4ac)) / (2a) - Discriminant:
D = b² - 4ac- If
D > 0: Two distinct real roots. - If
D = 0: Two equal real roots (x = -b / 2a). - If
D < 0: No real roots (roots are imaginary).
- If
📈 3. Arithmetic Progressions (AP)
An Arithmetic Progression is a sequence where each term is obtained by adding a fixed common difference d to the preceding term.
- Common Difference:
d = a₂ - a₁ = aₙ - aₙ₋₁(Can be positive, zero, or negative). - nth Term of an AP:
aₙ = a + (n - 1)d(whereais the first term,nis number of terms). - nth Term from End:
l - (n - 1)d(wherelis the last term). - Sum of First n Terms:
Sₙ = (n / 2) · [2a + (n - 1)d]ORSₙ = (n / 2) · [a + l] - Relation between Sₙ and aₙ:
aₙ = Sₙ - Sₙ₋₁.
📍 4. Coordinate Geometry
Let point A(x₁, y₁) and B(x₂, y₂) lie in a Cartesian plane:
- Distance Formula:
AB = √[(x₂ - x₁)² + (y₂ - y₁)²] - Distance from Origin (0, 0):
OP = √(x² + y²) - Section Formula (Internal Division in ratio m₁ : m₂):
P(x, y) = [ (m₁x₂ + m₂x₁) / (m₁ + m₂), (m₁y₂ + m₂y₁) / (m₁ + m₂) ] - Midpoint Formula:
M(x, y) = [ (x₁ + x₂) / 2, (y₁ + y₂) / 2 ] - Centroid of Triangle ABC:
G(x, y) = [ (x₁ + x₂ + x₃) / 3, (y₁ + y₂ + y₃) / 3 ]
📐 5. Complete Trigonometry Handbook
In right-angled triangle ABC (right-angled at B):
- Basic Ratios:
sin θ = Perpendicular / Hypotenuse,cos θ = Base / Hypotenuse,tan θ = Perpendicular / Base,cosec θ = 1 / sin θ,sec θ = 1 / cos θ,cot θ = 1 / tan θ. - Fundamental Trigonometric Identities:
1.sin²θ + cos²θ = 1→sin²θ = 1 - cos²θ,cos²θ = 1 - sin²θ
2.1 + tan²θ = sec²θ→sec²θ - tan²θ = 1
3.1 + cot²θ = cosec²θ→cosec²θ - cot²θ = 1 - Standard Angle Values Table:
sin 0° = 0,sin 30° = 1/2,sin 45° = 1/√2,sin 60° = √3/2,sin 90° = 1cos 0° = 1,cos 30° = √3/2,cos 45° = 1/√2,cos 60° = 1/2,cos 90° = 0tan 0° = 0,tan 30° = 1/√3,tan 45° = 1,tan 60° = √3,tan 90° = Not Defined
📦 6. Surface Areas, Volumes & Statistics
A. 3D Geometry Formula Sheet:
- Right Circular Cylinder: CSA =
2πrh| TSA =2πr(r + h)| Volume =πr²h - Right Circular Cone: Slant height
l = √(r² + h²)| CSA =πrl| TSA =πr(l + r)| Volume =(1/3)πr²h - Sphere: Surface Area =
4πr²| Volume =(4/3)πr³ - Hemisphere: CSA =
2πr²| TSA =3πr²| Volume =(2/3)πr³
B. Statistics & Probability:
- Direct Mean:
x̄ = Σ(fᵢxᵢ) / Σfᵢ - Assumed Mean Method:
x̄ = a + [ Σ(fᵢdᵢ) / Σfᵢ ](wheredᵢ = xᵢ - a) - Mode of Grouped Data:
Mode = l + [ (f₁ - f₀) / (2f₁ - f₀ - f₂) ] × h - Median of Grouped Data:
Median = l + [ ((n/2) - cf) / f ] × h - Empirical Relationship:
3 × Median = Mode + 2 × Mean - Probability:
P(E) = Number of outcomes favourable to E / Total number of possible outcomes. (0 ≤ P(E) ≤ 1andP(E) + P(not E) = 1).
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