Chapter 2: Problem 57
Find the derivative of the function. $$ y=x\left(5^{3 x}\right) $$
Short Answer
Expert verified
The short version of the answer is: \(y'(x)= 5^{3x}(1 + 3x\cdot ln5 )\)
Step by step solution
01
Identify the two functions to apply the Product Rule
Let's define the two functions that we have a product of:
Function 1: \(f(x) = x\)
Function 2: \(g(x) = 5^{3x}\)
02
Apply the Product Rule
The Product Rule states that if we have a function y(x) that is the product of two functions f(x)g(x), then the derivative of y(x) with respect to x is given by:
\( y'(x) = f'(x)g(x) + f(x)g'(x) \)
So, first, we'll find the derivatives of both functions, f'(x) and g'(x), individually.
03
Find the derivative of f(x)
Since f(x) = x is a simple function, its derivative is straightforward:
\( f'(x) = 1 \)
04
Find the derivative of g(x) using the Chain Rule
The Chain Rule states that if we have a function y(x) = h(u(x)), then the derivative of y(x) with respect to x is given by:
\( y'(x) = h'(u(x))\cdot u'(x) \)
So, let's apply this rule to our g(x) function:
Function: \(g(x) = 5^{3x}\)
Inner function: \(u(x) = 3x\)
Outer function: \(h(u) = 5^u\)
First, find the derivative of both the inner and outer functions:
u'(x) = 3 (derivative of 3x)
h'(u) = 5^u \cdot ln5 (derivative of 5^u)
Now, apply the Chain Rule to find g'(x):
\( g'(x) = h'(u(x))\cdot u'(x) = 5^{3x} \cdot ln5 \cdot 3 \)
05
Combine derivatives using the Product Rule
Now that we have f'(x) and g'(x), we can use the Product Rule to find the derivative of y(x):
\( y'(x) = f'(x)g(x) + f(x)g'(x) = 1\cdot 5^{3x} + x\cdot 3\cdot 5^{3x}\cdot ln5 \)
So the derivative of the given function is:
\( y'(x)= 5^{3x}(1 + 3x\cdot ln5 ) \)
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Product Rule
The Product Rule is a crucial tool in calculus for finding the derivative of a product of two functions. If you have a function, say \(y = f(x) \cdot g(x)\), the Product Rule helps us differentiate it. According to the rule, the derivative \(y'(x)\) is given by the formula:\[y'(x) = f'(x)g(x) + f(x)g'(x)\]This means we need to:
- Find the derivative of the first function, \(f(x)\).
- Multiply it by the second function, \(g(x)\), without differentiating it yet.
- Next, find the derivative of the second function, \(g(x)\).
- Multiply that by the first function, \(f(x)\), in its original form.
Chain Rule
The Chain Rule is a fundamental principle for finding derivatives of composite functions. It is especially helpful when dealing with nested functions, where one function is "inside" another. Consider a composite function \(y(x) = h(u(x))\), where \(h\) acts on an inside function \(u(x)\). The Chain Rule states:\[y'(x) = h'(u(x)) \cdot u'(x)\]In this approach:
- First, find \(u'(x)\), the derivative of the inner function \(u(x)\).
- Then, find \(h'(u)\), the derivative of the outer function \(h\), but treat \(u(x)\) as a constant.
- Finally, multiply these two derivatives together to get the overall derivative.
Exponential Functions
Exponential functions are unique because they involve continuous growth or decay, characterized by the form \(a^{x}\), where \(a\) is a constant base. They play a crucial role in differentiation due to their distinct property: the derivative of an exponential function \(a^{u(x)}\) remains proportional to the function itself. Specifically,\[\frac{d}{dx}(a^{u(x)}) = a^{u(x)} \cdot u'(x) \cdot \ln(a) \]When differentiating, always remember:
- Identify \(u(x)\), the exponent that can be any differentiable function.
- Differentiate \(u(x)\) to find \(u'(x)\).
- Multiply \(a^{u(x)}\) by the derivative \(u'(x)\) and by \(\ln(a)\).