89.0k views
2 votes
Find the inflection points of f(x) = x��� - x�� - 45x�� + 8.

User Epaga
by
7.4k points

1 Answer

2 votes

Final answer:

To find the inflection points of the function f(x) = x⁴ - x³ - 45x² + 8, we need to find the second derivative, set it equal to zero to find potential inflection points, and then confirm these points by analyzing the change in concavity around them.

Step-by-step explanation:

The question asks to find the inflection points of the function f(x) = x⁴ - x³ - 45x² + 8. To do this, we need to perform the following steps:

  • Find the second derivative of the function, f''(x).
  • Set the second derivative equal to zero and solve for x to find potential inflection points.
  • Test the intervals around the solutions to confirm whether the concavity changes, which signifies an inflection point.

Let's begin with the first derivative of f(x):

f'(x) = 4x³ - 3x² - 90x

Now, we calculate the second derivative:

f''(x) = 12x² - 6x - 90

Set f''(x) to zero and solve for x:

0 = 12x² - 6x - 90

Finally, we solve the quadratic equation to find the potential inflection points and test intervals to confirm the inflection points.

User Renesis
by
8.2k points