Determine the point where the function f(x) = 2x^3 - 9x^2 + 12x has a local mini

Practice Questions

Q1
Determine the point where the function f(x) = 2x^3 - 9x^2 + 12x has a local minimum. (2023)
  1. (1, 5)
  2. (2, 0)
  3. (3, 3)
  4. (4, 4)

Questions & Step-by-Step Solutions

Determine the point where the function f(x) = 2x^3 - 9x^2 + 12x has a local minimum. (2023)
  • 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). The derivative 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.
  • Step 8: To find out if these points are local minima or maxima, we can use the second derivative test or check the values of f(x) around these points.
  • Step 9: Calculate f(2) to find the function value at x = 2: f(2) = 2(2)^3 - 9(2)^2 + 12(2) = 0.
  • Step 10: Since we are looking for a local minimum, we check the second derivative or the behavior of f(x) around x = 2.
  • Finding Local Minima – The question tests the ability to find local minima of a function using calculus, specifically by finding critical points through the first derivative.
  • Critical Points – Identifying where the first derivative equals zero to find potential local extrema.
  • Second Derivative Test – Understanding that further analysis (like the second derivative test) is needed to confirm whether the critical point is a minimum or maximum.
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