If the function f (x) = {(x 2   - 1)/(x - 1) when x ≠ 1,  k when x = 1 } is given to be continuous at x = 1, then the value of k is ________ 

If the function f(x) = {(x^2  - 1)/(x - 1) when x ≠ 1,  k when x = 1 }

Question 12 - CBSE Class 12 Sample Paper for 2020 Boards - Part 2

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Transcript

Question 12 If the function 𝑓(π‘₯)={(π‘₯^2 βˆ’ 1)/(π‘₯ βˆ’ 1) π‘€β„Žπ‘’π‘› π‘₯β‰ 1 @π‘˜ π‘€β„Žπ‘’π‘› π‘₯=1 )─is given to be continuous at x = 1, then the value of k is ________ Since f(x) is continuous at x = 1, then lim┬(xβ†’1) 𝑓(π‘₯)=𝑓(1) lim┬(xβ†’1) ((π‘₯^2 βˆ’ 1)/(π‘₯ βˆ’ 1)) =π‘˜ lim┬(xβ†’1) (((π‘₯ βˆ’ 1)(π‘₯ + 1))/(π‘₯ βˆ’ 1)) =π‘˜ lim┬(xβ†’1) (π‘₯+1) =π‘˜ 1 + 1 = k 2 = k k = 2 Therefore, k = 2

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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.