I want to see the plot of an inverse function -- can I use a TI84?

[barryj]

TL;DR Summary

I am studying inverse functions and want to see a plot of an inverse function.

Summary: I am studying inverse functions and want to see a plot of an inverse function.

I hope this is an OK post here.

Lets say I have a function y = x^3 + x. This function has n inverse sine the derivitave is always positive and is a one on one function.

I can easily graph this function using my TI84. How can I graph the inverse function. This is what I have tried and failed at.

Set the TI84 to graph x^3 + x. Now look at the table of values. L1 is X, and L2 is f(x).
I thought I could use the stat plot option and set L2 to X and L1 to f(x) and then graph both the original function and its inverse using the stat plot feature.

Is there a way to do what I want?

 

[WWGD]

In theory,there is a general formula to solve a cubic , called Cardano's formula,where you can solve for x in terms of y but i don't think it is very practical.

 

[mfb]

If you just want to see how the inverse function looks, rotate your calculator (and plot -f(x) or f(-x) to get positive values going up).

 

[barryj]

I wasn't thinking about a cubic in particular but a function in general. I used Excel to plot the function and its inverse but I would like to use the TI84.

I can use the table feature to get a list of values of f(x) vs X, but how can I plot X vs f(x)? Maybe not possible unless I write a special program.

 

[WWGD]

I wasn't thinking about a cubic in particular but a function in general. I used Excel to plot the function and its inverse but I would like to use the TI84.

I can use the table feature to get a list of values of f(x) vs X, but how can I plot X vs f(x)? Maybe not possible unless I write a special program.

I don't understand,why not just relabel x as f(x) and viceversa and then just plot them?

 

[barryj]

When I plot a function, the TI84 fills the table with values. However, this table is not the same as you would have if you entered the values manually and used Statplot to plot the two graphs. I can make two plots manually but it is a bit klunky.

 

[mfb]

My comment about rotating the calculator was serious.

 

[barryj]

I see your point

 

[sysprog]

On my TI-83 in $\mathtt {func}$ mode there's a $\mathtt {DrawInv}$ option. If it is selected from the $\mathtt {DRAW}$ menu, the machine will return to the home screen or the program editor. It's not interactive. $\mathtt {DrawInv}$ puts $\mathtt x$ values on the $\mathtt y$ axis and vice versa. It takes a single expression as an argument (not a list of expressions). You can invert a matrix by using the $\mathtt {^{-1}}$ key. The matrix must be square and the determinant can't be zero.

 

[KurtChris]

My comment about rotating the calculator was serious.

Sure,i can see you are very professional.

 

[sysprog]

Sure,i can see you are very professional.

@mfb's suggestion was spot on: if you just want to see the inverse of a graph that is already displayed, you can simply rotate the device $90^\circ$ in the display plane, and then mentally swap the $\mathtt x$ and $\mathtt y$ axes to their normal positions.