How Do You Solve the Difference Quotient for f(x) = 4 + 3x - x^2?

W5rIGF0IHRoZSBOQVJNQVRFIFN0YXRlbWVudCBpcyAKZihsZWFndWUoMSopIC0gZihsZWFndWUoMyArMSkgLSB4KQ==In summary, the conversation is about someone having trouble with difference quotient questions and needing help with a specific question involving the function f(x) = 4 + 3x - x^2. They are asked to evaluate the difference quotient and simplify the answer, but are struggling to do so. The conversation ends with a clarification on the notation and suggestions on how to solve the problem.
  • #1
nukeman
655
0

Homework Statement



I am having trouble with a couple difference quotient questions. Here is a question I can't seem to solve.

Evaluate the difference quotient for the given funtion and simplify your answer.

f(x) = 4 + 3x - x^2 , f(3 + h) - f(3) / h




Homework Equations





The Attempt at a Solution



I have tried it a couple times, and can't seem to get it right! Any help at all would be great!
Thanks.
 
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  • #2
Remember the difference quotient is:

f(x) = (f(x+h)-f(x))/h

Since you say that f(x) = 4 + 3x - x^2 plug that in for f(x) in the equation. I don't know why you would plug in f(3).
 
  • #3
nukeman said:

Homework Statement



I am having trouble with a couple difference quotient questions. Here is a question I can't seem to solve.

Evaluate the difference quotient for the given funtion and simplify your answer.

f(x) = 4 + 3x - x^2 , f(3 + h) - f(3) / h




Homework Equations





The Attempt at a Solution



I have tried it a couple times, and can't seem to get it right! Any help at all would be great!
Thanks.



Should we assume you mean [f(3+h) - f(3)]/h, rather than what you wrote (which meant f(3+h) - [f(3)/h])? Anyway, if you meant the first one, what is stopping you from substituting x = 3+h into the formula and simplifying it, then substituting x = 3 and simplifying (or setting h = 0 in your first result)? When you say you can't get it right, how do know your results are wrong? Are you given an answer, and cannot seem to match it?

RGV
 

Related to How Do You Solve the Difference Quotient for f(x) = 4 + 3x - x^2?

1. What is the difference quotient?

The difference quotient is a mathematical concept used to find the average rate of change of a function over a given interval. It is represented by the formula (f(x+h) - f(x)) / h, where h represents the change in the independent variable and f(x) represents the function.

2. How is the difference quotient used in calculus?

In calculus, the difference quotient is used to find the derivative of a function. By taking the limit of the difference quotient as h approaches 0, we can find the instantaneous rate of change of the function at a specific point.

3. What is the significance of the difference quotient?

The difference quotient is significant because it allows us to calculate the rate of change of a function, which is important in many real-world applications. It also serves as the foundation for finding the derivative, which is a fundamental concept in calculus.

4. Can you provide an example of a difference quotient?

Sure, let's say we have the function f(x) = x^2. To find the difference quotient for this function at x = 3, we would use the formula (f(3+h) - f(3)) / h. Substituting in the values, we get ((3+h)^2 - 9) / h. Simplifying this expression gives us (9 + 6h + h^2 - 9) / h, which simplifies further to 6 + h. As h approaches 0, the difference quotient becomes 6, which is the slope of the tangent line at x = 3.

5. Are there any limitations to using the difference quotient?

One limitation is that it can only be used to find the derivative of a function at a single point. To find the derivative at multiple points, we would need to use other techniques such as the power rule or chain rule. Additionally, the difference quotient may not work for all types of functions, such as those with discontinuities or vertical asymptotes.

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