Identify the coordinates of any local maximum and minimum points for the function y = x^3 - 3x + 3 and select the correct answers from the options given.
Understand the Problem
The question asks for the identification of local maximum and minimum points of the function y = x^3 - 3x + 3, requiring the user to select the correct answers based on the graph provided.
Answer
Local maximum: $(-1, 5)$; Local minimum: $(1, 1)$.
Answer for screen readers
The local maximum point is at $(-1, 5)$ and the local minimum point is at $(1, 1)$.
Steps to Solve
- Find the derivative of the function To identify local maximum and minimum points, we first need the derivative of the function. Given the function
$$ y = x^3 - 3x + 3 $$
the derivative is:
$$ y' = 3x^2 - 3 $$
- Set the derivative to zero Next, we set the derivative equal to zero to find critical points:
$$ 3x^2 - 3 = 0 $$
This simplifies to:
$$ x^2 = 1 $$
- Solve for critical points By taking the square root, we find the critical points:
$$ x = 1 \quad \text{and} \quad x = -1 $$
- Determine the nature of the critical points To classify the critical points, we can use the second derivative test. We calculate the second derivative:
$$ y'' = 6x $$
Now we evaluate the second derivative at the critical points:
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For $x = 1$: $$ y''(1) = 6(1) = 6 \quad (\text{positive, indicates a local minimum}) $$
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For $x = -1$: $$ y''(-1) = 6(-1) = -6 \quad (\text{negative, indicates a local maximum}) $$
- Find the function values at critical points Now, we evaluate the original function at these critical points to find their coordinates:
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For $x = -1$: $$ y(-1) = (-1)^3 - 3(-1) + 3 = -1 + 3 + 3 = 5 $$ Thus, the local maximum point is at $(-1, 5)$.
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For $x = 1$: $$ y(1) = (1)^3 - 3(1) + 3 = 1 - 3 + 3 = 1 $$ Thus, the local minimum point is at $(1, 1)$.
The local maximum point is at $(-1, 5)$ and the local minimum point is at $(1, 1)$.
More Information
The function $y = x^3 - 3x + 3$ is a cubic polynomial, which can have both local maxima and minima. The points identified here are critical to understanding the function's behavior graphically.
Tips
- Confusing local maxima and minima by misinterpreting the results from the second derivative test.
- Failing to evaluate the function at critical points which makes it impossible to determine their coordinates.
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