Piecewise Function: Find Expression for Graph | Homework Help

As long as you choose one function for [0,3] and the other for (3,5), you will get the correct graph. In summary, the solution to the given problem is to choose the first function, y = -x + 3, for the interval [0,3] and the second function, y = 2x - 6, for the interval (3,5). This will result in the given curve. The choice of intervals is arbitrary, as long as they do not overlap and the correct functions are chosen for each interval.
  • #1
Rijad Hadzic
321
20

Homework Statement


Hello I uploaded a picture of the image.

Find an expression for a function who's graph is the given curve.

Homework Equations

The Attempt at a Solution


The first function [0,3] y= -x+3 and the second one is y=2x-6 from 3 to 5

what I don't get, is why isn't the second one [3,5], instead the answer is (3,5)..

The way I see it at that point, x=3, it can be anyone of those equations...
 

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  • #2
My thinking is because the function goes from right to left it would make sense that the first function is less than or equal to 3 but I'm not sure if that's right..
 
  • #3
Rijad Hadzic said:

Homework Statement


Hello I uploaded a picture of the image.

Find an expression for a function who's graph is the given curve.

Homework Equations

The Attempt at a Solution


The first function [0,3] y= -x+3 and the second one is y=2x-6 from 3 to 5

what I don't get, is why isn't the second one [3,5], instead the answer is (3,5)..

The way I see it at that point, x=3, it can be anyone of those equations...
And that's why you should choose which function goes with which interval. If ##x \in [0. 3]## you use the formula y = -x + 3. If ##x \in (3, 5)##, you use the formula y = 2x - 6.
 
  • #4
Mark44 said:
And that's why you should choose which function goes with which interval. If ##x \in [0. 3]## you use the formula y = -x + 3. If ##x \in (3, 5)##, you use the formula y = 2x - 6.

So the reason my books answer was [0,3] for y=-x + 3 was because they chose it to be that.

But if I wanted to I could choose [0,3) for y=-x+3 and [3,5] for 2x - 6 and my answer would still be valid because that's what I decided to choose?
 
  • #5
Rijad Hadzic said:
So the reason my books answer was [0,3] for y=-x + 3 was because they chose it to be that.

But if I wanted to I could choose [0,3) for y=-x+3 and [3,5] for 2x - 6 and my answer would still be valid because that's what I decided to choose?
Yes. At x = 3, both functions have y-values of 0, so it doesn't matter how you define the endpoints of the two intervals.
 

What is a piecewise function and how is it different from a regular function?

A piecewise function is a function that is defined by different expressions for different intervals, or "pieces", of the input. This means that the function may have different rules for different parts of the input domain. In contrast, a regular function has one single rule that applies to the entire input domain.

How do I find the expression for a piecewise function given its graph?

To find the expression for a piecewise function, you will need to carefully examine the graph and identify the different intervals and their corresponding rules. Then, you can write out the expression for each interval separately, making sure to incorporate any necessary adjustments, such as shifting or reflecting the graph.

Can a piecewise function have more than two pieces?

Yes, a piecewise function can have as many pieces as needed to accurately represent the different rules for different parts of the input domain. This means that a piecewise function can have two, three, four, or even more pieces, depending on the complexity of the function.

What are some real-life applications of piecewise functions?

Piecewise functions are commonly used in fields such as economics, engineering, and physics to model real-life situations that involve changing rules or conditions. For example, a piecewise function could be used to model a company's production costs, where different rules apply for different levels of production.

Are there any common mistakes to avoid when working with piecewise functions?

Yes, some common mistakes when working with piecewise functions include forgetting to include all necessary intervals and their corresponding rules, not considering any necessary adjustments to the graph, and not carefully labeling the intervals and their corresponding rules. It is important to be thorough and precise when working with piecewise functions to accurately represent the function's behavior.

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