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Test the continuity of the following function at the point or interval indicated against them: f(x) ,for,,for,for=x2+8x-202x2-9x+10, for 0<x<3, x≠2=12, for x=2=2-2x-x2x-4, for 3≤x<4} at x = 2

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Question

Test the continuity of the following function at the point or interval indicated against them:

f(x) `{:( =(x^2 + 8x - 20)/(2x^2 - 9x + 10)",",  "for"  0 < x < 3","  x ≠ 2),(= 12",",  "for"  x = 2),(= (2 - 2x - x^2)/(x - 4)",",  "for"  3 ≤ x < 4):}}` at x = 2

Sum
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Solution

f(2) = 12           ...(Given)         ...(1)

`lim_(x -> 2) "f"(x) =  lim_(x -> 2) (x^2 + 8x - 20)/(2x^2 - 9x + 10)`

= `lim_(x -> 2) ((x - 2)(x + 10))/((x - 2)(2x - 5))`

= `lim_(x -> 2) (x + 10)/(2x - 5)`                 ...`[(∵ x → 2 x ≠ 2),(∴  x → 2 ≠ 0)]`   

= `(lim_(x -> 2) (x + 10))/(lim_(x -> 2) (2x - 5))`

= `(2 + 10)/(4 - 5)`

= – 12                      ...(2)

From (1) and (2),

`lim_(x ->  2) "f"(x) ≠ f(2)`

∴ f is discontinuous at x = 2.

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Chapter 8: Continuity - EXERCISE 8.1 [Page 173]

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