Example 3 - Prove 1/1.2 + 1/2.3 + 1/3.4 .. + 1/n(n + 1) = 1/n+1 - Equal - 1 upon addition

Example 3 - Chapter 4 Class 11 Mathematical Induction - Part 2
Example 3 - Chapter 4 Class 11 Mathematical Induction - Part 3 Example 3 - Chapter 4 Class 11 Mathematical Induction - Part 4

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Example 3 For all n ≥ 1, prove that 1/1.2 + 1/2.3 + 1/3.4 +…….+ 1/(𝑛(𝑛 + 1)) = 1/(𝑛 + 1) Let P (n) : 1/1.2 + 1/2.3 + 1/3.4 +…….+ 1/(𝑛(𝑛 + 1)) = 1/(𝑛 + 1) For n=1, L.H.S = 1/1.2 = 1/2 R.H.S = 1/(1+1) = 1/2 Hence, L.H.S. = R.H.S , ∴ P(n) is true for n = 1 Assume P(k) is true 1/1.2 + 1/2.3 + 1/3.4 +…….+ 1/(𝑘(𝑘+1)) = 𝑘/(𝑘+1) We will prove that P(k + 1) is true. R.H.S = ((k + 1))/(((k + 1)+ 1) ) L.H.S =1/1.2 + 1/2.3 + 1/3.4 +…….+ 1/((k + 1)((k + 1)+ 1)) ∴ By the principle of mathematical induction, P(n) is true for n, where n is a natural number

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Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 13 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.