How to get a function that changes depending on x

[tmt1]

Hi,

I want to write a function whereby if x > 2 the function is one thing, and if x <= 2 it is something else.

How could I write this with latex?

 

[MarkFL]

When you are composing your post, look below the posting area to the $\LaTeX$ Live Preview element. on the bottom row, you will see a button labeled "Begin/End" which will allow you to easily compose things using the begin/end environment, among these are piecewise functions.

So, click the "Begin/End" button, and then from the drop-down menu, choose "Piecewise Function" and then in the first input element, give the function's name, such as $f(x)$, and then in the other input element, define each function piece, and its domain, separated by a comma.

Once you have this defined, then click "Submission Options" and choose the tags with which you wish for the code to be wrapped, and whether you want this to be inserted in the live preview, or for it to replace what is there, then if you are finished, click "Submit/Close" and the code will be generated in the live preview, and it you like what you see, you can copy this code to your post message, at the current cursor location there using the "Copy to Post" button.

If you are not certain what $\LaTeX$ codes to use for your definitions, use the Quick $\LaTeX$ element to the right, from which you can choose the symbols you will need.

 

[Prove It]

Hi,

I want to write a function whereby if x > 2 the function is one thing, and if x <= 2 it is something else.

How could I write this with latex?

How about this?

$\displaystyle \begin{align*} \left| 2 - x \right| = \begin{cases} 2 - x \textrm{ if } x \leq 2 \\ x- 2 \textrm{ if } x > 2 \end{cases} \end{align*}$

If you hover over the LaTeX you will see the code.

 

[tmt1]

How about this?

$\displaystyle \begin{align*} \left| 2 - x \right| = \begin{cases} 2 - x \textrm{ if } x \leq 2 \\ x- 2 \textrm{ if } x > 2 \end{cases} \end{align*}$

If you hover over the LaTeX you will see the code.

Thanks that is what I was looking for

 

[alphy]

To write this function in LaTeX, you can use the "piecewise" function, which allows you to specify different expressions for different intervals of the variable x. Here is an example of how you can write this function:

$f(x) = \begin{cases} 2x+1 & \text{if } x > 2 \\ x^2+3 & \text{if } x \leq 2 \end{cases}$

In this example, the function has two different expressions depending on the value of x. If x is greater than 2, the function is equal to 2x+1. If x is less than or equal to 2, the function is equal to x^2+3. You can change the expressions to fit your specific function.