Chapter 1: Problem 60
Simplify the difference quotients\(\frac{f(x+h)-f(x)}{h}\) and \(\frac{f(x)-f(a)}{x-a}\) for the following functions. $$f(x)=2 x^{2}-3 x+1$$
Short Answer
Expert verified
a) \(\frac{f(x+h)-f(x)}{h}\)
b) \(\frac{f(x)-f(a)}{x-a}\)
Answer:
a) \(4x+2h-3\)
b) \(2(x+a)-3\)
Step by step solution
01
Calculate \(f(x+h)\)
Replace \(x\) with \(x+h\) in the given function:
$$f(x+h)=2 (x+h)^{2}-3 (x+h)+1$$
02
Expand and simplify \(f(x+h)\)
Expand and combine like terms:
$$f(x+h)=2(x^2+2xh+h^2)-3x-3h+1$$
$$f(x+h)=2x^2+4xh+2h^2-3x-3h+1$$
03
Calculate \(f(x+h)-f(x)\)
Subtract \(f(x)\) from \(f(x+h)\) to find the difference:
$$(f(x+h)-f(x))=(2x^2+4xh+2h^2-3x-3h+1)-(2x^2-3x+1)$$
Simplify by removing the brackets and then subtracting the corresponding terms:
$$f(x+h)-f(x)=4xh+2h^2-3h$$
04
Simplify the first difference quotient \(\frac{f(x+h)-f(x)}{h}\)
Divide the difference \(f(x+h)-f(x)\) by \(h\):
$$\frac{f(x+h)-f(x)}{h}=\frac{4xh+2h^2-3h}{h}$$
Factor out an \(h\) from the numerator and simplify:
$$\frac{f(x+h)-f(x)}{h}=\frac{h(4x+2h-3)}{h}=4x+2h-3$$
Now we'll work with the second difference quotient:
05
Calculate \(f(x)-f(a)\)
Replace \(x\) with \(a\) in the given function and subtract it from \(f(x)\):
$$(f(x)-f(a))=(2x^2-3x+1)-(2a^2-3a+1)$$
Simplify by removing the brackets and subtracting corresponding terms:
$$f(x)-f(a)=2x^2-2a^2-3x+3a$$
06
Simplify the second difference quotient \(\frac{f(x)-f(a)}{x-a}\)
Divide the difference \(f(x)-f(a)\) by \(x-a\):
$$\frac{f(x)-f(a)}{x-a}=\frac{2x^2-2a^2-3x+3a}{x-a}$$
Factor out a 2 from the first two terms and a 3 from the last two terms in the numerator:
$$\frac{f(x)-f(a)}{x-a}=\frac{2(x^2-a^2)-3(x-a)}{x-a}$$
Now, notice that the first term in the numerator is a difference of squares, and the second term is a common factor. Simplify further:
$$\frac{f(x)-f(a)}{x-a}=\frac{2(x-a)(x+a)-3(x-a)}{x-a}$$
Factor \((x-a)\) from the numerator:
$$\frac{f(x)-f(a)}{x-a}=2(x+a)-3$$
Now we have simplified both difference quotients:
$$\frac{f(x+h)-f(x)}{h}=4x+2h-3$$
$$\frac{f(x)-f(a)}{x-a}=2(x+a)-3$$
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.
Derivative
In calculus, the concept of a derivative is fundamental. It measures the rate at which a function changes at any given point. Essentially, derivatives give us the slope of the tangent line to a function's graph at a specific point.
The formal definition of a derivative at a point is given by the limit of the difference quotient:
The formal definition of a derivative at a point is given by the limit of the difference quotient:
- As the change in input (often represented as \(h\) or \(x-a\)) approaches zero.
- This results in an instantaneous rate of change.
Function Simplification
To grasp the behavior of functions, simplifying complex expressions is often necessary. Function simplification involves reducing expressions to a more manageable form without altering their intrinsic value.
This is accomplished by:
This is accomplished by:
- Combining like terms
- Expanding expressions
- Cancelling common factors
Algebraic Manipulation
Algebraic manipulation is a powerful tool in mathematics that involves rearranging and simplifying expressions using algebraic rules. This skill is crucial in calculus, especially when dealing with complex functions and expressions.
- Basic operations include expanding expressions, factoring, and simplifying fractions.
- For expressions containing a difference of squares, recognizing this form aids in swift simplification.