Questions: Question 15
Identify the function's local and absolute extreme values, if any, saying where they occur.
h(x) = (x-1)/(x^2+3x+5)
no local extrema
local minimum at x=-3; local maximum at x=4
local minimum at x=-2 ; no local maxima
local minimum at x=-2; local maximum at x=4
Transcript text: Question 15
Identify the function's local and absolute extreme values, if any, saying where they occur.
\[
h(x)=\frac{x-1}{x^{2}+3 x+5}
\]
no local extrema
local minimum at $x=-3$; local maximum at $x=4$
local minimum at $x=-2 ;$ no local maxima
local minimum at $x=-2$; local maximum at $x=4$
Solution
Solution Steps
To find the local and absolute extreme values of the function \( h(x) = \frac{x-1}{x^2+3x+5} \), we need to:
Compute the derivative \( h'(x) \) to find critical points by setting \( h'(x) = 0 \).
Use the second derivative test or the first derivative test to determine the nature of each critical point (local minimum, local maximum, or neither).
Evaluate the function at critical points and endpoints (if any) to find absolute extrema.
Step 1: Find the Derivative
We start with the function \( h(x) = \frac{x-1}{x^2 + 3x + 5} \). The first derivative is calculated as follows:
\[
h'(x) = \frac{(-2x - 3)(x - 1) + (1)(x^2 + 3x + 5)}{(x^2 + 3x + 5)^2}
\]
Step 2: Identify Critical Points
Setting the first derivative \( h'(x) = 0 \) allows us to find the critical points. Solving this gives us:
\[
\text{Critical Points: } x = -2, \, 4
\]
Step 3: Determine the Nature of Critical Points
Next, we compute the second derivative \( h''(x) \) to classify the critical points:
\[
h''(x) = \frac{(-4x - 6)(-2x - 3)(x - 1) + 2(-2x - 3)(x^2 + 3x + 5) - 2(x - 1)(x^2 + 3x + 5)}{(x^2 + 3x + 5)^3}
\]
Evaluating \( h''(-2) \) and \( h''(4) \):
For \( x = -2 \): \( h''(-2) > 0 \) indicates a local minimum.
For \( x = 4 \): \( h''(4) < 0 \) indicates a local maximum.
Final Answer
The function has a local minimum at \( x = -2 \) and a local maximum at \( x = 4 \). Thus, the answer is:
\[
\boxed{\text{local minimum at } x = -2; \text{ local maximum at } x = 4}
\]