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AP EAMCET2006MathematicsApplication of Derivatives

In the interval (-3,3) the function f(x)= x 3 + 3 x , x 0 is :

Options

  1. Aincreasing
  2. Bdecreasing
  3. Cneither increasing nor decreasing
  4. Dpartly increasing and partly decreasing

Correct answer

B. decreasing

Step-by-step solution

f(x)= x 3 + 3 x f^ (x)= 1 3 - 3 x^2 It is clear that f^ (x) is less than zero in the interval (-3,3) . Thus f(x) is decreasing in the interval (-3,3) .

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