Chapter 3: Problem 14
Find the linear approximation to each function and evaluate it at the given values of \(x\) and \(d x\). \(\sqrt{x}\) at \(x=16\) and \(d x=-2\)
Short Answer
Expert verified
The linear approximation is \( \frac{15}{4} \).
Step by step solution
01
Identify the Function and Point of Tangency
The function we need to find the linear approximation for is \( f(x) = \sqrt{x} \). We will perform the approximation around the point where \( x = 16 \).
02
Find the Derivative of the Function
Calculate the derivative of \( f(x) = \sqrt{x} \). Using the power rule, the derivative is \( f'(x) = \frac{1}{2\sqrt{x}} \).
03
Evaluate the Derivative at the Given Point
Evaluate the derivative at \( x = 16 \). Thus, \( f'(16) = \frac{1}{2\sqrt{16}} = \frac{1}{8} \).
04
Write the Linear Approximation Formula
The linear approximation (or tangent line) at \( x = a \) is given by the formula: \( L(x) = f(a) + f'(a)(x - a) \). Here, \( a = 16 \).
05
Substitute Values into the Linear Approximation
Substitute \( a = 16 \), \( f(16) = \sqrt{16} = 4 \), and \( f'(16) = \frac{1}{8} \) into the formula: \[ L(x) = 4 + \frac{1}{8}(x - 16) \].
06
Evaluate the Linear Approximation at \( x = 16 + dx \)
Substitute \( x = 16 + (-2) = 14 \) into the approximation: \[ L(14) = 4 + \frac{1}{8}(14 - 16) = 4 + \frac{1}{8}(-2) = 4 - \frac{1}{4} = \frac{16}{4} - \frac{1}{4} = \frac{15}{4} \].
07
Final Answer
The linear approximation of \( \sqrt{x} \) at \( x = 16 \) for \( dx = -2 \) is \( \frac{15}{4} \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Calculus
Calculus is a fundamental branch of mathematics that studies rates of change and accumulation. It's like having a mathematical toolkit that helps us understand how things change and accumulate over time. Calculus is divided into two main branches:
- Differential Calculus: Focuses on the concept of the derivative, which represents rates of change.
- Integral Calculus: Concerns itself with accumulation and areas under curves.
Derivative
The derivative is a central concept in differential calculus. It measures how a function changes as its input changes. Think of it as the function's rate of change at a particular point.
- If a function describes a road's slope, the derivative will tell you how steep the road is at any given point.
- A positive derivative indicates an increasing function, while a negative derivative signifies a decreasing function.
Tangent Line
A tangent line to a curve at a given point is the straight line that touches the curve at that point. The line doesn’t cross the curve at the immediate vicinity of the point; it just touches it.
- The slope of the tangent line is given by the derivative of the function at that point.
- For example, at \(x = 16\) for \(f(x) = \sqrt{x}\), the slope is \(f'(16) = \frac{1}{8}\).
Function Evaluation
Function evaluation is the process of finding the output of a function given a particular input. It involves substituting the input value into the function to determine its output.
- For instance, evaluating \(f(x) = \sqrt{x}\) at \(x = 16\) gives \(f(16) = \sqrt{16} = 4\).
- This output is used when calculating the linear approximation.