Chapter 1: Problem 66
$$ \begin{array}{l} \text { For each function, find and simplify }\\\ \frac{f(x+h)-f(x)}{h} . \quad(\text { Assume } h \neq 0 .) \end{array} $$ $$ f(x)=3 x^{2}-5 x+2 $$
Short Answer
Expert verified
The simplified expression is \( 6x + 3h - 5 \).
Step by step solution
01
Understand the Function
We are given a quadratic function \( f(x) = 3x^2 - 5x + 2 \). We need to find the expression \( \frac{f(x+h)-f(x)}{h} \). This expression is crucial for understanding the rate of change of the function and is related to the derivative.
02
Substitute \( x+h \) into the Function
Substitute \( x+h \) into the function \( f(x) \):\[ f(x+h) = 3(x+h)^2 - 5(x+h) + 2 \]Simplify this expression by expanding the binomials.
03
Expand and Simplify \( f(x+h) \)
First expand \((x+h)^2\) to get \(x^2 + 2xh + h^2\). Then substitute:\[ f(x+h) = 3(x^2 + 2xh + h^2) - 5(x+h) + 2 \]Simplify further:\[ = 3x^2 + 6xh + 3h^2 - 5x - 5h + 2 \].
04
Find \( f(x+h) - f(x) \)
Calculate \( f(x+h) - f(x) \) by substituting in the expressions for \( f(x+h) \) and \( f(x) \):\[ f(x+h) - f(x) = (3x^2 + 6xh + 3h^2 - 5x - 5h + 2) - (3x^2 - 5x + 2) \]Simplify:\[ = 6xh + 3h^2 - 5h \].
05
Divide by \( h \) and Simplify
Now divide the expression from Step 4 by \( h \):\[ \frac{f(x+h) - f(x)}{h} = \frac{6xh + 3h^2 - 5h}{h} \]Factor \( h \) out from the numerator:\[ = \frac{h(6x + 3h - 5)}{h} \]Cancel out \( h \) to simplify:\[ = 6x + 3h - 5 \].
06
Conclusion
The expression \( \frac{f(x+h)-f(x)}{h} \) simplifies to \( 6x + 3h - 5 \). This shows the average rate of change of the function around \( x \) as \( h \) approaches 0.
Unlock Step-by-Step Solutions & Ace Your Exams!
-
Full Textbook Solutions
Get detailed explanations and key concepts
-
Unlimited Al creation
Al flashcards, explanations, exams and more...
-
Ads-free access
To over 500 millions flashcards
-
Money-back guarantee
We refund you if you fail your exam.
Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!
Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Quadratic Function
A quadratic function is a polynomial function of degree two, generally expressed in the form \( f(x) = ax^2 + bx + c \). It is characterized by the presence of the term \( x^2 \), which imparts a parabolic shape to the graph of the function. In our specific problem, the quadratic function given is \( f(x) = 3x^2 - 5x + 2 \).Key features of quadratic functions include:
- The vertex, which is the highest or lowest point of the parabola depending on the sign of \( a \).
- The axis of symmetry, a vertical line that passes through the vertex and divides the parabola into two mirror images.
- The direction of the parabola, which opens upwards if \( a > 0 \) and downwards if \( a < 0 \).
Rate of Change
The rate of change is a fundamental concept that describes how a function's output changes with respect to changes in the input. For a function \( f(x) \), the rate of change over an interval is determined by the difference quotient, which is expressed as \( \frac{f(x+h) - f(x)}{h} \).In the context of the given quadratic function, the simplified difference quotient \( 6x + 3h - 5 \) is used. This expression tells us how the output of the quadratic changes as \( h \) changes, providing an average rate of change over a small interval around \( x \).Understanding the rate of change:
- Helps us anticipate the behavior of the function over an interval.
- Indicates how fast or slow the function's value is increasing or decreasing.
Derivative
The derivative of a function is a central concept in calculus that represents the instantaneous rate of change of the function with respect to one of its variables. When \( h \) approaches zero, the difference quotient \( \frac{f(x+h) - f(x)}{h} \) transforms into the derivative.In relation to our quadratic function, as \( h \to 0 \), the expression \( 6x + 3h - 5 \) simplifies to \( 6x - 5 \). This is the derivative of the quadratic function \( f(x) = 3x^2 - 5x + 2 \).Key insights from derivatives:
- They provide critical information about the function's increasing or decreasing behavior at a specific point.
- Derivatives allow us to find the slope of the tangent to the function's graph at any point \( x \).
- By identifying where the derivative equals zero, we can locate the function's critical points, which help determine maxima, minima, or inflection points.