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Maxima & Minima · Question 32 of 80

Question 32

EasyOriginal question

What is the local minimum value of f(x)=x3−3x+2f(x) = x^{3} - 3 x + 2?

Options for question 32

Show the answer and explanation
CorrectNot quiteAnswer B

Correct answer: B

Explanation

  1. f′(x)=3(x−1)(x+1)=0f'(x) = 3 \left(x - 1\right) \left(x + 1\right) = 0 at x=−1x = -1 and x=1x = 1.

  2. f′′(x)=6xf''(x) = 6 x: f′′(1)=6f''(1) = 6, so x=1x = 1 is a local minimum.

  3. The value there is f(1)=0f(1) = 0.

Worth noting

11 is where it happens, not the value; and 44 is the local maximum.

Concept
Local maximum and minimum values
Typical time
60 s
Your time
—
The rule this testsThe second derivative test
Practise this chapter →

Ten questions from Maxima & Minima, at your own pace.

Practise this chapter →

Ten questions from Maxima & Minima, at your own pace.