Find the x-coordinate of the point where the function f(x) = 2x^3 - 9x^2 + 12x h

Practice Questions

Q1
Find the x-coordinate of the point where the function f(x) = 2x^3 - 9x^2 + 12x has a local maximum.
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  2. 2
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Questions & Step-by-Step Solutions

Find the x-coordinate of the point where the function f(x) = 2x^3 - 9x^2 + 12x has a local maximum.
Correct Answer: 1
  • Step 1: Write down the function f(x) = 2x^3 - 9x^2 + 12x.
  • Step 2: Find the derivative of the function, which is f'(x). This tells us the slope of the function.
  • Step 3: Calculate the derivative: f'(x) = 6x^2 - 18x + 12.
  • Step 4: Set the derivative equal to zero to find critical points: 6x^2 - 18x + 12 = 0.
  • Step 5: Simplify the equation by dividing everything by 6: x^2 - 3x + 2 = 0.
  • Step 6: Factor the quadratic equation: (x - 1)(x - 2) = 0.
  • Step 7: Solve for x: This gives us x = 1 and x = 2 as critical points.
  • Step 8: To determine if these points are local maxima or minima, find the second derivative f''(x).
  • Step 9: Calculate the second derivative: f''(x) = 12x - 18.
  • Step 10: Evaluate the second derivative at x = 1: f''(1) = 12(1) - 18 = -6.
  • Step 11: Since f''(1) < 0, this indicates a local maximum at x = 1.
  • Step 12: Therefore, the x-coordinate of the point where the function has a local maximum is x = 1.
  • Finding Local Extrema – The question tests the ability to find local maxima and minima of a function using first and second derivative tests.
  • Critical Points – Identifying critical points by setting the first derivative to zero is essential for determining local extrema.
  • Second Derivative Test – Using the second derivative to confirm whether a critical point is a local maximum or minimum.
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