Basics Questions on Sequence & Series

Duration: 6 min

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Module outline

  1. About the Course: About the Course
  2. Paper-1 & 2 | Basic Numeracy: Ratio and Proportion (Ratios), Divisibility Rules, Mixture and Alligation, Permutation and Combination, Logarithm, Number System, HCF LCM, Sequence and Series (Series), Speed Time and Distance, Percentage, Average, Mensuration and Geometry, Age Problems, Arithmetic, Statistics, Probability, Profit and Loss, Simple Interest and Compound Interest, Partnership, Speed Mathematics and Basic Mathematics, Algebra, Powers and Exponents (Surds and Indices), Time and Work, Pipe and Cistern, RSSB Specific Videos - Basic Numeracy
  3. Paper-1 & 2 | Data Interpretation: Data Interpretation
  4. Paper-1 & 2 | General Mental Ability: Mental Ability, RSSB Specific Videos - Mental Ability
  5. Paper-1 & 2 | Logical Reasoning and Analytical Ability: Series (Number and Letter Series) (Numerical Relations and Reasoning), Coding Decoding, Data Sufficiency, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning), Syllogisms, Seating Arrangements, Blood Relations, Directions (Direction Test), Analytical Reasoning (Counting Figures Reasoning), Puzzle Solving (Puzzles), Calendar, Clock, Cubes & Dices, Venn Diagram, Analogy, Ranking, Order and Sequence, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Data Arrangement, Logical Sequence Of Words, Crypt Arithmetic
  6. Paper-1 & 2 | Decision Making and Problem Solving: Selection Decision Table (Decision Making)
  7. Paper-1 | General Science: Physics, Biology, Chemistry, RSSB Specific Videos
  8. Paper-1 | General Awareness: State Wise GK, GK- Current Affairs
  9. Paper-2 | Fundamentals of Computer: Basics of COA, Number System, Floating Point Rep, Number Representation
  10. Paper - 2 | Digital Logic Systems: Digital Systems & Boolean Basics, Logic Gates & Hardware, Boolean Expression, Boolean Minimization, Combinational Circuit, Sequential Circuits
  11. Paper-2 | Operating Systems: Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Deadlock, Threads & Process Creation, Memory Management, Virtual Memory, Disc Scheduling, File Management, Linux OS, Distributed Systems
  12. Paper-2 | Database Management System: Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, Relational Algebra, SQL, Relational Calculus, File Organization & Indexing, Transaction Management, Concurrency Control
  13. Paper-2 | Data Structures: Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing
  14. Paper-2 | C Programming: C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling
  15. Paper 2 | Oops, C++, Java: Language Design, OOPS with C++, Java, .Net Programming, Java Fundamentals
  16. Paper 2 | Python: Introduction to Python, Tokens, Variables, Data Types, I/O, Operators & Expressions, Control Flow & Looping, Collections & Strings, Functions & Modules, File Handling & Data Analysis
  17. Paper 2 | Emerging Trends and AI: Emerging Tech Trends, Artificial Intelligence
  18. Paper-2 | Algorithms: Algorithm Analysis, Time Complexity Analysis, Sorting Algorithms, Greedy Algorithms, Advanced Algorithms
  19. Paper 2 | Data Communication and Network Security: Introduction to CN, Data Communication, DLL: Access Control, DLL: Flow Control, DLL: Error Control, Data Link Layer - Ethernet, Net Layer: IPv4 & Proto, Net Layer: IP Addressing, Net Layer:Routing Protocol, Transport Layer Services, TL: Congestion & UDP, Application Layer, Hardware basics, Network Security, Ethical Hacking
  20. Paper-2 I Software Engineering: Fundamentals of Software Engineering, Software Requirements and Quality Assurance, Software Design, Estimation and Metrics, Software Testing, Software Maintenance and Configuration Management
  21. Paper-2 | Computer Organization and Architecture: Cache Memory Organization, Input Output Organisation, Instr Formats & Modes, Control Unit Design, Register Transfer and Microoperations
  22. Paper-2 | Web Development: JavaScript-Basics, HTML Basics, CSS, XML
  23. Pedagogy: Child Development, Concept of Pedagogy, Psychology, Theories, Inclusive Education, Experiential Pedagogy, Curriculum Framework & Reforms, National Education Policy (NEP) 2020
  24. Live Sessions: RSSB Live Sessions
  25. RSSB Paper 1 - Full Mock Tests:
  26. RSSB Paper 2 - Full Mock Tests:
  27. SCI Previous Year Papers:
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

This educational video is a lecture on sequences and series, specifically focusing on arithmetic progressions (AP). The instructor, Yash Jain, begins by introducing the topic with a title card and then presents a series of problems to demonstrate the application of key formulas. The first problem asks for the sum of an AP with 12 terms, a first term of -19, and a last term of 36. The instructor writes down the formula for the sum of an AP, S_n = n/2 (a + a_n), and substitutes the given values to calculate the sum as 66. The second problem involves an AP with 17 terms, a first term of -20, and a last term of 28, which is solved using the same formula to find a sum of 136. The final problem is a multiple-choice question where the relationship 7 times the 7th term equals 11 times the 11th term is given, and the task is to find the 18th term. The instructor uses the general term formula, a_n = a + (n-1)d, to set up the equation 7(a+6d) = 11(a+10d), which simplifies to -4a = 68d, or a = -17d. Substituting this into the formula for the 18th term, a_18 = a + 17d, results in a_18 = -17d + 17d = 0. The video concludes with a 'Thanks for Watching' screen.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The video opens with an animated title card for a lesson on 'SEQUENCE & SERIES'. The screen displays a cartoon boy at a desk with a chalkboard that shows the formula for the sum of a series, S_N = a1 + a2 + a3 + ... + aN. The instructor, Yash Jain, is visible in a small window in the bottom right corner. The title card also includes the text 'Basic To Advance' and 'KNOWLEDGE GATE EDUCATOR'. The instructor then introduces the first problem: 'In an AP, there are 12 terms, the first term is -19 and last term is 36. Find the sum of AP?'. He begins to solve it by writing down the given values: AP, n=12, a=-19, a_n=36.

  2. 2:00 – 5:00 02:00-05:00

    The instructor proceeds to solve the first problem. He writes the formula for the sum of an arithmetic progression: S_n = n/2 (a + a_n). He substitutes the values from the problem: S_12 = 12/2 (-19 + 36). He then performs the calculation: S_12 = 6 * 17, which equals 102. He then moves to the second problem: 'In an AP, there are 17 terms, the first term is -20 and last term is 28. Find the sum of AP?'. He writes down the values: AP, n=17, a=-20, a_n=28. He applies the same formula: S_17 = 17/2 (-20 + 28). He calculates: S_17 = 17/2 * 8 = 17 * 4 = 68. He then transitions to the third problem, a multiple-choice question: 'If 7 times of the seventh term of an AP is equal to 11 times its eleventh term, then the 18th term of the AP will be __'. He writes the given condition: 7a_7 = 11a_11.

  3. 5:00 – 6:23 05:00-06:23

    The instructor begins solving the third problem. He writes the general formula for the nth term of an AP: a_n = a + (n-1)d. He then expresses the 7th and 11th terms: a_7 = a + 6d and a_11 = a + 10d. He substitutes these into the given equation: 7(a + 6d) = 11(a + 10d). He expands the equation: 7a + 42d = 11a + 110d. He rearranges the terms to get: 7a - 11a = 110d - 42d, which simplifies to -4a = 68d. He then solves for a: a = -17d. The question asks for the 18th term, so he writes a_18 = a + 17d. He substitutes a = -17d into this formula: a_18 = -17d + 17d = 0. The video ends with a 'Thanks for Watching' screen.

The video presents a structured lesson on arithmetic progressions, progressing from basic sum calculations to a more complex problem involving the relationship between terms. The core teaching method is the step-by-step application of formulas. The first two problems demonstrate the direct use of the sum formula S_n = n/2 (a + a_n) with given values. The third problem requires a deeper understanding, using the general term formula a_n = a + (n-1)d to establish a relationship between the first term (a) and the common difference (d), which is then used to find a specific term. The key insight is that the 18th term is independent of the specific values of a and d, as the relationship forces it to be zero. This demonstrates a powerful problem-solving technique in algebra.

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