. Given f(x)=-x²+4x+12, 05x58: (a) Carefully, graph f(x), 0sxs8.

Trigonometry (MindTap Course List)
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ChapterP: Prerequisites
SectionP.7: A Library Of Parent Functions
Problem 47E
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In need of help with b and c

 

**Problem 3: Given \( f(x) = -x^2 + 4x + 12 \), \( 0 \leq x \leq 8 \):**

**(a) Carefully, graph \( f(x) \), \( 0 \leq x \leq 8 \).**

**Solution:**
To graph the function \( f(x) = -x^2 + 4x + 12 \) for the domain \( 0 \leq x \leq 8 \), follow these steps:

1. **Identify Key Points:**
   - **Vertex:** The vertex of a quadratic function \( ax^2 + bx + c \) can be found using \( x = -\frac{b}{2a} \).
     For \( f(x) = -x^2 + 4x + 12 \):
     \[
     a = -1, \quad b = 4, \quad c = 12
     \]
     \[
     x = -\frac{4}{2(-1)} = 2
     \]
     Substituting \( x = 2 \) into \( f(x) \) to find \( y \):
     \[
     f(2) = -(2)^2 + 4(2) + 12 = -4 + 8 + 12 = 16
     \]
     The vertex is at \( (2, 16) \).

2. **Find the Y-Intercept:**
   To find the y-intercept, set \( x = 0 \):
   \[
   f(0) = -(0)^2 + 4(0) + 12 = 12
   \]
   So, the y-intercept is \( (0, 12) \).

3. **Find the X-Intercepts:**
   To find the x-intercepts, set \( f(x) = 0 \):
   \[
   -x^2 + 4x + 12 = 0
   \]
   Solving the quadratic equation:
   \[
   x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}
   \]
   \[
   x = \frac{-4 \pm \sqrt{16 + 48}}{-2}
   \]
   \[
   x = \frac
Transcribed Image Text:**Problem 3: Given \( f(x) = -x^2 + 4x + 12 \), \( 0 \leq x \leq 8 \):** **(a) Carefully, graph \( f(x) \), \( 0 \leq x \leq 8 \).** **Solution:** To graph the function \( f(x) = -x^2 + 4x + 12 \) for the domain \( 0 \leq x \leq 8 \), follow these steps: 1. **Identify Key Points:** - **Vertex:** The vertex of a quadratic function \( ax^2 + bx + c \) can be found using \( x = -\frac{b}{2a} \). For \( f(x) = -x^2 + 4x + 12 \): \[ a = -1, \quad b = 4, \quad c = 12 \] \[ x = -\frac{4}{2(-1)} = 2 \] Substituting \( x = 2 \) into \( f(x) \) to find \( y \): \[ f(2) = -(2)^2 + 4(2) + 12 = -4 + 8 + 12 = 16 \] The vertex is at \( (2, 16) \). 2. **Find the Y-Intercept:** To find the y-intercept, set \( x = 0 \): \[ f(0) = -(0)^2 + 4(0) + 12 = 12 \] So, the y-intercept is \( (0, 12) \). 3. **Find the X-Intercepts:** To find the x-intercepts, set \( f(x) = 0 \): \[ -x^2 + 4x + 12 = 0 \] Solving the quadratic equation: \[ x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \] \[ x = \frac{-4 \pm \sqrt{16 + 48}}{-2} \] \[ x = \frac
### Calculus Problem: Finding Net Area and Evaluating Integrals

#### Problem Statement
(b) Find the net area from \( x = 0 \) and \( x = 8 \).

(c) Evaluate \( \int_{0}^{8} \lvert f(x) \rvert \, dx \).

#### Solution Approach

To solve these problems, we need to understand the concept of net area and the integral of the absolute value of a function over an interval.

**Net Area:**
The net area between a function \( f(x) \) and the x-axis from \( x = 0 \) to \( x = 8 \) is found by evaluating the definite integral:
\[ \text{Net Area} = \int_{0}^{8} f(x) \, dx \]

The net area considers the function's regions above the x-axis as positive and regions below the x-axis as negative.

**Area under the Absolute Value Function:**
To find the total area between the function \( f(x) \) and the x-axis considering all regions as positive (regardless of the function dipping below the x-axis), we evaluate:
\[ \int_{0}^{8} \lvert f(x) \rvert \, dx \]

This integral sums the absolute values of the function over the interval, treating all areas as positive.

### Summary
- The net area from \( x = 0 \) to \( x = 8 \) is the integral \( \int_{0}^{8} f(x) \, dx \).
- The total area, treating all regions as positive, is \( \int_{0}^{8} \lvert f(x) \rvert \, dx \).
Transcribed Image Text:### Calculus Problem: Finding Net Area and Evaluating Integrals #### Problem Statement (b) Find the net area from \( x = 0 \) and \( x = 8 \). (c) Evaluate \( \int_{0}^{8} \lvert f(x) \rvert \, dx \). #### Solution Approach To solve these problems, we need to understand the concept of net area and the integral of the absolute value of a function over an interval. **Net Area:** The net area between a function \( f(x) \) and the x-axis from \( x = 0 \) to \( x = 8 \) is found by evaluating the definite integral: \[ \text{Net Area} = \int_{0}^{8} f(x) \, dx \] The net area considers the function's regions above the x-axis as positive and regions below the x-axis as negative. **Area under the Absolute Value Function:** To find the total area between the function \( f(x) \) and the x-axis considering all regions as positive (regardless of the function dipping below the x-axis), we evaluate: \[ \int_{0}^{8} \lvert f(x) \rvert \, dx \] This integral sums the absolute values of the function over the interval, treating all areas as positive. ### Summary - The net area from \( x = 0 \) to \( x = 8 \) is the integral \( \int_{0}^{8} f(x) \, dx \). - The total area, treating all regions as positive, is \( \int_{0}^{8} \lvert f(x) \rvert \, dx \).
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