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NCERT Class XI Mathematics - Limits and Derivatives - Solutions
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Question : 30 of 72
Marks:
+1,
-0
If f (x) = . For what value(s) of a does f (x) exists ?
Solution:
We have f (x) = Case (i) : When a < 0, we have f (x) = |x| + 1 = (- x + 1) = - a + 1 Case (ii) : When a > 0, we have f (x) = (x - 1) = a - 1 Case (iii) : When a = 0, we have = f (x) = f (x) = (|x| - 1) = 0 - 1 = - 1 = f (x) = (|x| + 1) = - 0 + 1 = 1 ∴ f (x) ≠ f (0) [Since f (0) = 0] f (x) does not exist when a = 0. ∴ f (x) exists for all a ≠ 0.
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