Absolute function into piecewise function

In summary, the conversation is about writing F(x)=x2-5|x| as a piecewise function. The attempt at a solution resulted in Fx=x2-5(x) and x2-5(-x), but the book's answer is x2-5 and x2-5(-x). It is likely a typo in the book, as the original attempt at solution seems to be correct. The conversation also discusses the importance of indicating the range when setting out piecewise functions.
  • #1
Astraithious
20
0

Homework Statement


Write F(x)= x2-5|x| as a piecewise function

Homework Equations

The Attempt at a Solution


I was writting it out and came to
Fx= x2-5(x) and x2-5(-x)

but my book says that it comes out to be
x2-5
x2-5(-x)

I imagine there is a very simple reason why the x in the first one disappears but i would love an explanation, thank you!
 
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  • #2
Astraithious said:

Homework Statement


Write F(x)= x2-5|x| as a piecewise function

Homework Equations

The Attempt at a Solution


I was writting it out and came to
Fx= x2-5(x) and x2-5(-x)

but my book says that it comes out to be
x2-5
x2-5(-x)

I imagine there is a very simple reason why the x in the first one disappears but i would love an explanation, thank you!
Looks like a typo in the book.

For positive x, you indeed get F(x)=x²-5x, and for negative x you get F(x)=x²+5x.
 
  • #3
Astraithious said:

Homework Statement


Write F(x)= x2-5|x| as a piecewise function

Homework Equations

The Attempt at a Solution


I was writting it out and came to
Fx= x2-5(x) and x2-5(-x)

but my book says that it comes out to be
x2-5
x2-5(-x)

I imagine there is a very simple reason why the x in the first one disappears but i would love an explanation, thank you!

You can verify that the book is wrong by filling in x values
 
  • #4
Astraithious said:

Homework Statement


Write F(x)= x2-5|x| as a piecewise function

Homework Equations

The Attempt at a Solution


I was writting it out and came to
Fx= x2-5(x) and x2-5(-x)

but my book says that it comes out to be
x2-5
x2-5(-x)

I imagine there is a very simple reason why the x in the first one disappears but i would love an explanation, thank you!
Your answers appear to be identical with the book's so I don't know what your problem is. It would then be usual to write it in the form that Samy did, and also when setting out piecewise functions you have to indicate the range either side of the form.
 
  • #5
epenguin said:
Your answers appear to be identical with the book's so I don't know what your problem is.
No, the book has x2-5 instead of x2-5x.
 
  • #6
thank you everybody this was a great relief
 
  • #7
Knowing the answer that's what I read when I see something else!
 

What is an absolute function?

An absolute function is a mathematical function that returns the positive value of a number, regardless of its original sign. It is represented by the symbol |x|.

What is a piecewise function?

A piecewise function is a function that is defined by multiple sub-functions, with each sub-function being defined for a specific interval or set of intervals. This allows for different rules to be applied to different parts of the function's domain.

What is the difference between an absolute function and a piecewise function?

An absolute function is a specific type of function that always returns the positive value of a number, while a piecewise function is a more general concept that can combine multiple functions to create a more complex overall function.

How do you graph an absolute function into a piecewise function?

To graph an absolute function into a piecewise function, you first need to identify the intervals in which the function will change. Then, for each interval, you will graph the corresponding sub-function. Finally, you will connect the different parts of the graph to create a piecewise function.

What are some real-world applications of absolute functions into piecewise functions?

Absolute functions into piecewise functions are commonly used in economics, physics, and engineering to model complex relationships and systems. For example, they can be used to model the demand for a product based on different price ranges, the acceleration of an object based on different forces, or the flow of traffic through a city at different times of the day.

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