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Assume that \(f\) is differentiable for all \(x\). The signs of \(f^{\prime}\) are as follows. \(f^{\prime}(x)>0\) on \((-\infty,-4)\) \(f^{\prime}(x)<0\) on (-4,6) \(f^{\prime}(x)>0\) on \((6, \infty)\) Supply the appropriate inequality for the indicated value of \(c\). $$ g(x)=f(x-10) \quad g^{\prime}(8) \quad 0 $$

Short Answer

Expert verified
\(g^{\prime}(8) > 0\)

Step by step solution

01

Identify the relationship between the function g and f

The given \(g(x) = f(x-10)\) is a transformation of the function \(f(x)\). Specifically, it is a horizontal shift 10 units to the right of the function \(f(x)\). The derivative of \(g(x)\) is \(g^{\prime}(x) = f^{\prime}(x - 10)\), according to the chain rule.
02

Transform the signs of \(f^{\prime}(x)\) to get the signs for \(g^{\prime}(x)\)

Looking at the intervals given for \(f^{\prime}\), since the function \(f(x)\) is shifted 10 units to the right to get \(g(x)\), you also need to shift the signs of \(f^{\prime}\) 10 units to the right. Therefore, the signs of \(g^{\prime}\) are: \(g^{\prime}(x) > 0\) on \((-\infty, -4+10) = (-\infty, 6)\) \(g^{\prime}(x) < 0\) on \((-4+10, 6+10) = (6,16)\) \(g^{\prime}(x) > 0\) on \((6+10, \infty) = (16, \infty)\)
03

Determine the sign of \(g^{\prime}(8)\)

Observe that \(8\) falls into the first interval of \(g^{\prime}(x)\), which is \((-\infty, 6)\), and within this interval \(g^{\prime}(x) > 0\). Thus \(g^{\prime}(8) > 0\).

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Derivative transformations
Derivative transformations help us understand how the derivatives of functions change when these functions undergo transformations like shifts, reflections, or stretches. In simple terms, when you transform a function, its derivative transforms along with it.

When dealing with transformations, one common scenario is horizontal or vertical shifts. For example, if you have a function \(f(x)\) and you've shifted it horizontally to get a new function \(g(x) = f(x - a)\), the derivative of \(g(x)\), denoted \(g^{\prime}(x)\), relates to the derivative of \(f(x)\), denoted \(f^{\prime}(x)\), through the transformation \(g^{\prime}(x) = f^{\prime}(x - a)\).
  • If you shift the function horizontally by \(a\) units to the left, the derivative transformation involves substituting \((x + a)\) in the function's derivative.
  • This relationship allows us to predict changes in the derivative without recalculating it from scratch.
In essence, understanding derivative transformations is crucial for quickly adapting your knowledge of a function's behavior to its transformations.
Horizontal shifts in functions
Horizontal shifts in functions can significantly affect how functions behave and their resulting graphs. A horizontal shift involves moving the graph of a function left or right.

For example, consider a function \(f(x)\) being shifted to form a new function \(g(x) = f(x - a)\). In this case, the graph of \(f(x)\) moves "a" units to the right if \(a\) is positive, or "a" units to the left if \(a\) is negative. This shift doesn't affect the function's shape, just its position along the x-axis.
  • If \(a > 0\), the shift is to the right.
  • If \(a < 0\), the shift is to the left.
Understanding horizontal shifts is vital because it helps us understand how transformations affect a function's domain and critical points, like where it increases or decreases. These insights can then help predict how changes to the input affect the entire function.
Chain rule in calculus
The chain rule is a fundamental rule in calculus used to find the derivative of a composition of functions. Essentially, it helps us understand how to differentiate functions that are "inside" other functions.

Imagine you have two functions, \(f(x)\) and \(h(x)\), and you compose them to create \(g(x) = f(h(x))\). To find the derivative \(g^{\prime}(x)\), or \(d/dx[f(h(x))]\), the chain rule tells us:
  • First, differentiate the outer function \(f\) with respect to its argument, treating \(h(x)\) like \(x\), to get \(f^{\prime}(h(x))\).
  • Next, multiply the result by the derivative of the inner function \(h(x)\), which is \(h^{\prime}(x)\).
  • The result is the derivative of the composition: \(g^{\prime}(x) = f^{\prime}(h(x)) \cdot h^{\prime}(x)\).
This powerful rule simplifies the differentiation process when dealing with nested functions. With practice, the chain rule becomes an invaluable tool in any calculus toolkit, allowing for the easy handling of complex derivatives.

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Most popular questions from this chapter

The function \(f\) is differentiable on the interval [-1,1] . The table shows the values of \(f^{\prime}\) for selected values of \(x\). Sketch the graph of \(f\), approximate the critical numbers, and identify the relative extrema. $$\begin{array}{|l|c|c|c|c|} \hline x & -1 & -0.75 & -0.50 & -0.25 \\ \hline f^{\prime}(x) & -10 & -3.2 & -0.5 & 0.8 \\ \hline \end{array}$$ $$\begin{array}{|l|l|l|l|l|l|} \hline \boldsymbol{x} & 0 & 0.25 & 0.50 & 0.75 & 1 \\ \hline \boldsymbol{f}^{\prime}(\boldsymbol{x}) & 5.6 & 3.6 & -0.2 & -6.7 & -20.1 \\ \hline \end{array}$$

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