Permutations And Combinations — Revision Notes
WBJEE · Mathematics
Quick revision notes for Permutations And Combinations — key concepts, formulas, and definitions for WBJEE Mathematics preparation.
Revision Notes — Permutations And Combinations
Key concepts, formulas, and definitions from Permutations And Combinations for WBJEE Mathematics preparation.
Key Topics to Revise
Fundamental Principle of Counting
- Two basic principles: Multiplication Principle and Addition Principle
- Multiplication Principle: If first operation can be done in m ways and second in n ways, both together can be done in m × n ways
- Addition Principle: If one operation can be done in m ways OR another in n ways, either can be done in (m + n) ways
Factorial Notation and Basic Formulas
- n! = 1 × 2 × 3 × ... × (n-1) × n
- 0! = 1 by definition
- n! is undefined for negative numbers and fractions
Permutations
- Permutation is arrangement of objects in definite order
- Order matters in permutations
- ⁿPᵣ represents permutations of n objects taken r at a time
Combinations
- Combination is selection of objects where order doesn't matter
- ⁿCᵣ represents combinations of n objects taken r at a time
- Also written as C(n,r) or (n choose r)
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Key Concepts
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What topics are covered in Permutations And Combinations for WBJEE?
Permutations And Combinations is an important chapter in WBJEE Mathematics. It covers key concepts and formulas that are frequently tested in the exam. Key topics include: Fundamental Principle of Counting, Factorial Notation and Basic Formulas, Permutations, Combinations.
How important is Permutations And Combinations for WBJEE?
Permutations And Combinations is a frequently tested chapter in WBJEE Mathematics. Questions from this chapter appear regularly in previous year papers. There are 63 practice questions available for this chapter.
How to prepare Permutations And Combinations for WBJEE?
Start by understanding the core concepts, then solve practice questions. Focus on formulas and their applications. Use revision notes for quick review before the exam.