Class 11 Maths PMI Lecture 1

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The successful warrior is the average man, with laser-like focus. – Bruce Lee

Lecture - 1 Chapter 4 Principle of Mathematical Induction

Exercise 4.1

Introduction to Principle of mathematical induction, explanation using dominoes

Proof of Arithmetic Progression using PMI
\( a+(a+d)+(a+2d)+…+(a+(n-1)d) = \frac{n}{2} (2a+(n-1)d)\)

Question 1. \( 1+3+3^2+…+3^{n-1} = \frac{(3^n-1)}{2}\)

Question 2. \( 1^3+2^3+3^3+…+n^3= \left ( \frac{n(n+1)}{2} \right )^2\)

Question 3. \( 1+\frac{1}{(1+2)}+\frac{1}{(1+2+3)}+…+\frac{1}{(1+2+3+…+n)}=\frac{2n}{(n+1)}\)

Question 4. \( 1.2.3+2.3.4+…+n(n+1)(n+2)=\frac{n(n+1)(n+2)(n+3)}{4}\)

Question 5. \( 1.3+2.3^2+3.3^3+…+n.3^n=\frac{(2n-1)3^{n+1}+3}{4}\)

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