Chapter 1: Problem 9
Differentiate. $$y=(2 x+4)^{3}$$
Short Answer
Expert verified
\(\frac{dy}{dx} = 6(2x + 4)^2\)
Step by step solution
01
Apply the Chain Rule
To differentiate the function, use the chain rule. The chain rule states that if you have a composite function \(y = f(g(x))\), then the derivative \(y'\) can be found as \(f'(g(x)) \times g'(x)\). Here, \(y=((2x+4)^3)\). Let \(u = 2x + 4\). Then, \(y = u^3\).
02
Differentiate the Outer Function
Differentiate \(y=u^3\) with respect to \(u\). This gives \(\frac{dy}{du}=3u^2\).
03
Differentiate the Inner Function
Differentiate \(u = 2x + 4\) with respect to \(x\). This gives \(\frac{du}{dx}=2\).
04
Combine the Results
Now, use the chain rule to combine the results: \(\frac{dy}{dx} = \frac{dy}{du} \times \frac{du}{dx} = 3u^2 \times 2\).
05
Substitute Back \(u\)
Replace \(u\) with the original expression \(2x + 4\): \(\frac{dy}{dx} = 3(2x + 4)^2 \times 2 = 6(2x + 4)^2\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Chain Rule
The Chain Rule is a fundamental technique in calculus used for finding the derivative of composite functions. Imagine you have a function nested inside another function, like a Russian matryoshka doll.
To make things simpler, think of it as follows: if you have a function defined as \(y = f(g(x))\), then you can take its derivative using the rule: \(y' = f'(g(x)) \times g'(x)\). Basically, you'll first differentiate the outer function, and then multiply it by the derivative of the inner function.
To make things simpler, think of it as follows: if you have a function defined as \(y = f(g(x))\), then you can take its derivative using the rule: \(y' = f'(g(x)) \times g'(x)\). Basically, you'll first differentiate the outer function, and then multiply it by the derivative of the inner function.
Composite Function
A composite function is like a machine within a machine. The output of one function becomes the input for another. For example, in the function \(y=(2x + 4)^3\), \(2x + 4\) is nested inside the cube function \(u^3\). Let’s break this down:
By understanding this nesting, you can apply the Chain Rule more effectively.
- First, identify the inner function as \(u = 2x + 4\).
- Then the outer function becomes \(y = u^3\).
By understanding this nesting, you can apply the Chain Rule more effectively.
Differentiation Steps
To differentiate composite functions like \(y = (2x+4)^3\), follow these steps:
Step 1: Apply the Chain Rule
Express the original function in terms of a new variable. Here, we let \(u = 2x + 4\) and rewrite the function as \(y = u^3\).
Step 2: Differentiate the Outer Function
Take the derivative of \(y = u^3\) with respect to \(u\). This gives \(\frac{dy}{du} = 3u^2\).
Step 3: Differentiate the Inner Function
Now, differentiate \(u = 2x + 4\) with respect to \(x\), yielding \(\frac{du}{dx} = 2\).
Step 4: Combine the Results
Use the Chain Rule to get \( \frac{dy}{dx} = \frac{dy}{du} \times \frac{du}{dx} = 3u^2 \times 2\).
Step 5: Substitute Back \(u\)
Finally, replace \(u\) with \(2x + 4\) to find \(\frac{dy}{dx} = 6(2x+4)^2\).
Following these steps makes differentiation simpler and easier to understand.
Step 1: Apply the Chain Rule
Express the original function in terms of a new variable. Here, we let \(u = 2x + 4\) and rewrite the function as \(y = u^3\).
Step 2: Differentiate the Outer Function
Take the derivative of \(y = u^3\) with respect to \(u\). This gives \(\frac{dy}{du} = 3u^2\).
Step 3: Differentiate the Inner Function
Now, differentiate \(u = 2x + 4\) with respect to \(x\), yielding \(\frac{du}{dx} = 2\).
Step 4: Combine the Results
Use the Chain Rule to get \( \frac{dy}{dx} = \frac{dy}{du} \times \frac{du}{dx} = 3u^2 \times 2\).
Step 5: Substitute Back \(u\)
Finally, replace \(u\) with \(2x + 4\) to find \(\frac{dy}{dx} = 6(2x+4)^2\).
Following these steps makes differentiation simpler and easier to understand.