# How to Graph X in Terms of Y on a TI-84 Calculator

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The TI-84 calculator offers a number of built-in functions to solve and graph equations. Unfortunately, its core graphing options are limited to functions and equations that feature ​Y​ in terms of ​X​. It's less common that you'll need to graph ​X​ in terms of ​Y​, but if you do then the existing options won't quite cut it. Fortunately, the TI-84 allows you to import external apps and use them in much the same way as you would use the apps that ship with the calculator. The community-supported TI Calc repository contains a number of these external apps, including an app called XGraph by Joel Smith that lets you graph ​X​ in terms of ​Y​.

## What Does X in Terms of Y Mean?

For most equations, you graph ​Y​ in terms of ​X​. What this means is that your equation is based on the value of ​Y​, and it's interpreted through the value of ​X​; an example of this would be ​y​ = ​x​ + 1. The value of ​Y​ depends on what the value of ​X​ is, so for each ​X​ the corresponding ​Y​ value is equal to that ​X​ value plus 1. Graphing ​X​ in terms of ​Y​ turns this around. Instead of ​y​ = ​x​ + 1, you would create a graph out of ​x​ = ​y​ + 1. In this case, your ​X​ value is dependent on the value of ​Y​ and to calculate each ​X​ you take its corresponding ​Y​ value and add 1. Unfortunately, this isn't easy to graph on a TI-84 calculator unless you calculate and plot individual points by hand since the TI-84 doesn't have an "X=" option in its graphing functions.