dy Find for y=7x sin x+14x cos x-14 sln x. dy

Calculus: Early Transcendentals
8th Edition
ISBN:9781285741550
Author:James Stewart
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Chapter1: Functions And Models
Section: Chapter Questions
Problem 1RCC: (a) What is a function? What are its domain and range? (b) What is the graph of a function? (c) How...
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**Problem:**

Find \(\frac{dy}{dx}\) for \(y = 7x^2 \sin x + 14x \cos x - 14 \sin x\).

**Solution:**

To find \(\frac{dy}{dx}\), we need to differentiate each term of the function with respect to \(x\).

1. **Differentiate \(7x^2 \sin x\):**
   - Use the product rule: \((uv)' = u'v + uv'\)
   - Let \(u = 7x^2\) and \(v = \sin x\).
   - \(u' = 14x\)
   - \(v' = \cos x\)
   - The derivative is:
     \[
     (uv)' = (14x)(\sin x) + (7x^2)(\cos x)
     \]

2. **Differentiate \(14x \cos x\):**
   - Use the product rule again.
   - Let \(u = 14x\) and \(v = \cos x\).
   - \(u' = 14\)
   - \(v' = -\sin x\)
   - The derivative is:
     \[
     (uv)' = (14)(\cos x) + (14x)(-\sin x)
     \]

3. **Differentiate \(-14 \sin x\):**
   - The derivative of \(\sin x\) is \(\cos x\).
   - So, \(-14 \sin x\) becomes \(-14 \cos x\).

**Combine all parts:**

\[
\frac{dy}{dx} = (14x)(\sin x) + (7x^2)(\cos x) + (14)(\cos x) - (14x)(\sin x) - 14 \cos x
\]

Simplifying, we cancel out \((14x)(\sin x)\) terms:

\[
\frac{dy}{dx} = (7x^2)(\cos x)
\]

Therefore, the derivative is:

\[
\frac{dy}{dx} = 7x^2 \cos x
\]
Transcribed Image Text:**Problem:** Find \(\frac{dy}{dx}\) for \(y = 7x^2 \sin x + 14x \cos x - 14 \sin x\). **Solution:** To find \(\frac{dy}{dx}\), we need to differentiate each term of the function with respect to \(x\). 1. **Differentiate \(7x^2 \sin x\):** - Use the product rule: \((uv)' = u'v + uv'\) - Let \(u = 7x^2\) and \(v = \sin x\). - \(u' = 14x\) - \(v' = \cos x\) - The derivative is: \[ (uv)' = (14x)(\sin x) + (7x^2)(\cos x) \] 2. **Differentiate \(14x \cos x\):** - Use the product rule again. - Let \(u = 14x\) and \(v = \cos x\). - \(u' = 14\) - \(v' = -\sin x\) - The derivative is: \[ (uv)' = (14)(\cos x) + (14x)(-\sin x) \] 3. **Differentiate \(-14 \sin x\):** - The derivative of \(\sin x\) is \(\cos x\). - So, \(-14 \sin x\) becomes \(-14 \cos x\). **Combine all parts:** \[ \frac{dy}{dx} = (14x)(\sin x) + (7x^2)(\cos x) + (14)(\cos x) - (14x)(\sin x) - 14 \cos x \] Simplifying, we cancel out \((14x)(\sin x)\) terms: \[ \frac{dy}{dx} = (7x^2)(\cos x) \] Therefore, the derivative is: \[ \frac{dy}{dx} = 7x^2 \cos x \]
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