Questions: Learning Outcome O5: Problem 5 (1 point) Directions: Use the function f(x) below to answer the following questions. f(x) = x^4 - 50 x^2 - 7 Find the x-values(s) where f has a relative maximum / relative minimum. 1. Relative Maximum(s): 2. Relative Minimum(s):

Learning Outcome O5: Problem 5
(1 point)

Directions: Use the function f(x) below to answer the following questions.

f(x) = x^4 - 50 x^2 - 7

Find the x-values(s) where f has a relative maximum / relative minimum.
1. Relative Maximum(s): 
2. Relative Minimum(s):
Transcript text: Learning Outcome O5: Problem 5 (1 point) Directions: Use the function $f(x)$ below to answer the following questions. \[ f(x)=x^{4}-50 x^{2}-7 \] Find the $x$-values(s) where $f$ has a relative maximum / relative minimum. 1. Relative Maximum(s): $\square$ 2. Relative Minimum(s): $\square$
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Solution

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Solution Steps

To find the relative maximum and minimum of the function \( f(x) = x^4 - 50x^2 - 7 \), we need to follow these steps:

  1. Find the derivative: Compute the first derivative of the function, \( f'(x) \), to find the critical points.
  2. Solve for critical points: Set \( f'(x) = 0 \) and solve for \( x \) to find the critical points.
  3. Determine the nature of critical points: Use the second derivative test by computing \( f''(x) \). Evaluate \( f''(x) \) at each critical point to determine if it is a relative maximum or minimum.
Step 1: Find the First Derivative

The function is given by \( f(x) = x^4 - 50x^2 - 7 \). We compute the first derivative: \[ f'(x) = 4x^3 - 100x \]

Step 2: Solve for Critical Points

To find the critical points, we set the first derivative equal to zero: \[ 4x^3 - 100x = 0 \] Factoring out \( 4x \), we have: \[ 4x(x^2 - 25) = 0 \] This gives us the critical points: \[ x = -5, \quad x = 0, \quad x = 5 \]

Step 3: Determine the Nature of Critical Points

Next, we compute the second derivative: \[ f''(x) = 12x^2 - 100 \] We evaluate the second derivative at each critical point:

  • For \( x = -5 \): \[ f''(-5) = 12(-5)^2 - 100 = 300 - 100 = 200 \quad (\text{positive, relative minimum}) \]

  • For \( x = 0 \): \[ f''(0) = 12(0)^2 - 100 = -100 \quad (\text{negative, relative maximum}) \]

  • For \( x = 5 \): \[ f''(5) = 12(5)^2 - 100 = 300 - 100 = 200 \quad (\text{positive, relative minimum}) \]

Final Answer

The relative maximum occurs at \( x = 0 \) and the relative minima occur at \( x = -5 \) and \( x = 5 \). Thus, the final answers are:

  • Relative Maximum(s): \( \boxed{0} \)
  • Relative Minimum(s): \( \boxed{-5, 5} \)
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