9. Use a trig substitution to show that f steps. dx (1+x²)3/2 = √1+2+C. Be sure to clearly show all

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Chapter1: Functions And Models
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### Problem 9: Trigonometric Substitution

Use a trigonometric substitution to show that:

\[ \int \frac{dx}{(1+x^2)^{3/2}} = \frac{x}{\sqrt{1+x^2}} + C. \]

Be sure to clearly show all steps.

---

**Steps for the Solution:**

1. **Substitution:**
   Let \( x = \tan(\theta) \). Therefore, \( dx = \sec^2(\theta) d\theta \).

2. **Replacement in the Integral:**
   Substitute \( x = \tan(\theta) \) into \( (1 + x^2) \):
   \[
   1 + x^2 = 1 + \tan^2(\theta) = \sec^2(\theta).
   \]
   Thus, the integral becomes:
   \[
   \int \frac{\sec^2(\theta) d\theta}{(\sec^2(\theta))^{3/2}}.
   \]

3. **Simplifying the Integral:**
   Simplify \( (\sec^2(\theta))^{3/2} \):
   \[
   (\sec^2(\theta))^{3/2} = (\sec(\theta))^3.
   \]
   Therefore, the integral becomes:
   \[
   \int \frac{\sec^2(\theta) d\theta}{\sec^3(\theta)} = \int \frac{d\theta}{\sec(\theta)} = \int \cos(\theta) d\theta.
   \]

4. **Integrate:**
   \[
   \int \cos(\theta) d\theta = \sin(\theta) + C.
   \]

5. **Back-Substitution:**
   Recall \( x = \tan(\theta) \). We need to express \(\sin(\theta)\) in terms of \(x\):
   \[
   \sin(\theta) = \frac{\tan(\theta)}{\sqrt{1+\tan^2(\theta)}} = \frac{x}{\sqrt{1+x^2}}.
   \]

6. **Final Answer:**
   \[
   \sin(\theta) + C = \frac{x}{\sqrt{1+x^2}} + C.
   \]

Thus, we have shown that:
\[ 
\int \
Transcribed Image Text:### Problem 9: Trigonometric Substitution Use a trigonometric substitution to show that: \[ \int \frac{dx}{(1+x^2)^{3/2}} = \frac{x}{\sqrt{1+x^2}} + C. \] Be sure to clearly show all steps. --- **Steps for the Solution:** 1. **Substitution:** Let \( x = \tan(\theta) \). Therefore, \( dx = \sec^2(\theta) d\theta \). 2. **Replacement in the Integral:** Substitute \( x = \tan(\theta) \) into \( (1 + x^2) \): \[ 1 + x^2 = 1 + \tan^2(\theta) = \sec^2(\theta). \] Thus, the integral becomes: \[ \int \frac{\sec^2(\theta) d\theta}{(\sec^2(\theta))^{3/2}}. \] 3. **Simplifying the Integral:** Simplify \( (\sec^2(\theta))^{3/2} \): \[ (\sec^2(\theta))^{3/2} = (\sec(\theta))^3. \] Therefore, the integral becomes: \[ \int \frac{\sec^2(\theta) d\theta}{\sec^3(\theta)} = \int \frac{d\theta}{\sec(\theta)} = \int \cos(\theta) d\theta. \] 4. **Integrate:** \[ \int \cos(\theta) d\theta = \sin(\theta) + C. \] 5. **Back-Substitution:** Recall \( x = \tan(\theta) \). We need to express \(\sin(\theta)\) in terms of \(x\): \[ \sin(\theta) = \frac{\tan(\theta)}{\sqrt{1+\tan^2(\theta)}} = \frac{x}{\sqrt{1+x^2}}. \] 6. **Final Answer:** \[ \sin(\theta) + C = \frac{x}{\sqrt{1+x^2}} + C. \] Thus, we have shown that: \[ \int \
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