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Discuss the continuity of the function f(x) = |2x + 3|, at x = −32

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Question

Discuss the continuity of the function f(x) = |2x + 3|, at x = `(−3)/(2)`

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Solution

f(x) = |2x + 3|, x = `(−3)/(2)`

|2x + 3| = 2x + 3; `x ≥ (-3)/(2)`

= – (2x + 3); `x < (-3)/(2)`

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

= `lim_(x -> (-3^(-))/(2)) [- (2x + 3)]`

= `-[2((-3)/2) + 3]`

= 0

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

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

= `2 ((-3)/2) + 3`

= 0.

`"f"((-3)/2) = |2 ((-3)/2) + 3|`

= |0|

= 0

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

∴ f(x) is continuous at x = `(-3)/(2)`.

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Chapter 8: Continuity - EXERCISE 8.1 [Page 172]

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