Example 8 - Show f(x) = x3 - 3x2 + 4x is strictly increasing - Examples

part 2 - Example 8 - Examples - Serial order wise - Chapter 6 Class 12 Application of Derivatives

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Example 8 Show that the function f given by f (š‘„) = š‘„3 – 3š‘„2 + 4š‘„, š‘„ ∈ R is strictly increasing on R. f(š‘„) = š‘„3 – 3š‘„2 + 4š‘„ Finding f’(š’™) f’(š‘„) = 3š‘„2 – 3.2š‘„ + 4 f’(š‘„) = 3x2 – 6š‘„ + 4 f’(š‘„) = 3x2 – 6š‘„ + 3 + 1 f’(š‘„) = 3 (š‘„2 – 2š‘„ + 1) + 1 f’(š’™) = 3 (š’™ – 1)2 + 1 As square is a positive number, The value of f’(š‘„) will be always positive for every real number Hence f’(š’™) > 0 for all š‘„ ∈ R ∓ f(š‘„) is strictly increasing

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