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Examine the continuity of ,for,forf(x)=x2-9x -3, for x≠3=8, for x=3} at x = 3.

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Question

Examine the continuity of `f(x) = {:((x^2 - 9)/(x  - 3)",",  "for"  x ≠ 3),(=8",",  "for"  x = 3):}}` at x = 3.

Sum
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Solution

f(3) = 8  ...(1) (Given)

`lim_(x -> 3) f(x) =  lim_(x -> 3) (x^2 - 9)/(x - 3)`

= `lim_(x -> 3) ((x - 3)(x + 3))/(x - 3)`

= `lim_(x -> 3) (x + 3)`  ...[∵ x → 3, x ≠ 3, ∴ x – 3 ≠ 0]

= 3 + 3

= 6  ...(2)

From (1) and (2),

f(3) ≠ `lim_(x -> 3)` f(x)

∴ f is discontinuous at x = 3.

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Chapter 8: Continuity - EXERCISE 8.1 [Page 172]

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