Check sibling questions

Ex 5.1 ,6 - Find all points of discontinuity of f(x) = {2x + 3

Ex 5.1 ,6 - Chapter 5 Class 12 Continuity and Differentiability - Part 2
Ex 5.1 ,6 - Chapter 5 Class 12 Continuity and Differentiability - Part 3 Ex 5.1 ,6 - Chapter 5 Class 12 Continuity and Differentiability - Part 4

This video is only available for Teachoo black users

Get live Maths 1-on-1 Classs - Class 6 to 12


Transcript

Ex 5.1, 6 Find all points of discontinuity of f, where f is defined by 𝑓(𝑥)={█(2𝑥+3, 𝑖𝑓 𝑥≤[email protected]&2𝑥−3, 𝑖𝑓 𝑥>2)┤ 𝑓(𝑥)={█(2𝑥+3, 𝑖𝑓 𝑥≤[email protected]&2𝑥−3, 𝑖𝑓 𝑥>2)┤ Since we need to find continuity at of the function We check continuity for different values of x When x = 2 When x < 2 When x > 2 Case 1 : When x = 2 f(x) is continuous at 𝑥 =2 if L.H.L = R.H.L = 𝑓(2) if lim┬(x→2^− ) 𝑓(𝑥)=lim┬(x→2^+ ) " " 𝑓(𝑥)= 𝑓(2) Since there are two different functions on the left & right of 2, we take LHL & RHL . LHL at x → 2 lim┬(x→2^− ) f(x) = lim┬(h→0) f(2 − h) = lim┬(h→0) (2(2−ℎ)+3) = lim┬(h→0) (4−2ℎ+3) = lim┬(h→0) (7−2ℎ) = 7 − 0 = 7 RHL at x → 2 lim┬(x→2^+ ) f(x) = lim┬(h→0) f(2 + h) = lim┬(h→0) (2(2+ℎ)−3) = lim┬(h→0) (4−2ℎ−3) = lim┬(h→0) (1−2ℎ) = 1 − 0 = 1 Since L.H.L ≠ R.H.L f(x) is not continuous at x = 2 Case 2 : When x < 2 For x < 2, f(x) = 2x + 3 Since this a polynomial It is continuous ∴ f(x) is continuous for x < 2 Case 3 : When x > 2 For x > 2, f(x) = 2x − 3 Since this a polynomial It is continuous ∴ f(x) is continuous for x > 2 Hence, only x = 2 is point is discontinuity. f is continuous at all real numbers except 2. Thus, f is continuous for 𝐱 ∈ R − {2}

Ask a doubt
Davneet Singh's photo - Co-founder, Teachoo

Made by

Davneet Singh

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.