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If f(x) = |x|3, show that f"(x) exists for all real x and find it. - Mathematics

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प्रश्न

If f(x) = |x|3, show that f"(x) exists for all real x and find it.

योग
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उत्तर

Case I: When x ≥ 0

Here, f(x) = |x|3 = x3

∴ f'(x) = 3x2

f''(x) = 6x

Case II: When, x < 0

Here, f(x) = (−x)3 = −x3

∴ f'(x) = −3x2

f"(x) = −6x

Thus, f"(x) = `{(6x", if"  x>= 0),(-6x", if"  x < 0):}`

Hence f"(x) = 6|x|

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अध्याय 5: Continuity and Differentiability - Exercise 5.9 [पृष्ठ १९२]

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एनसीईआरटी Mathematics Part 1 and 2 [English] Class 12
अध्याय 5 Continuity and Differentiability
Exercise 5.9 | Q 18 | पृष्ठ १९२

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