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Identify discontinuities for the following function as either a jump or a removable discontinuity : f(x) =x2-3x-2, for x<-3=3+8x, for x>-3

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Question

Identify discontinuities for the following function as either a jump or a removable discontinuity :

f(x) `{:(= x^2 - 3x - 2",",  "for"  x < -3),(= 3 + 8x",",  "for"  x > -3):}`

Sum
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Solution

f(x) `{:(= x^2 - 3x - 2",",  x < -3),(= 3 + 8x",", x > -3):}`

f(x) is a polynomial function for both the intervals.

∴ f(x) is continuous for both the given intervals.

Let us test the continuity at x = − 3

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

= (− 3)2 − 3(− 3) − 2

= 9 + 9 − 2

= 16

`lim_(x -> -3^+) "f"(x) = lim_(x -> -3^+) (3 + 8x)`

= 3 + 8(− 3)

= − 21

∴ `lim_(x -> -3^-) "f"(x) ≠ lim_(x -> -3^+) "f"(x)`

∴ `lim_(x -> -3) "f"(x)` does not exist.

∴ f(x) is discontinuous at x = − 3

∴ f(x) has a jump discontinuity at x =− 3

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Chapter 8: Continuity - EXERCISE 8.1 [Page 173]

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