# How to Graph an Index of a Function

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Graphing an index of a function is something that you can do to avoid further memorization. Graph an index of a function with help from a professional private tutor in this free video clip.

Part of the Video Series: Math Questions & Answers
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## Video Transcript

Hi, I'm Rachel, and today we're going to be going over how to graph an index of a function. Creating an index for a function is a great way to then find the points on the graph because you don't have to memorize you know what the graph looks like you can literally just plot out the points you get from the index. So lets look at a function like x squared -1. We can write an index x and then x squared -1 and then find the y values. So we can literally plug in points and see where they're going to graph. Lets start with a point 0. We have 0 - 1. That gives us our y, that's -1. Lets then start with something like 1. That's gonna be 1 squared -1 so that's 1-1 is 0. Lets look at -1. We have -1 quantity squared - 1. That's again 1 - 1 which is 0. Lets add a few more points. Lets say we have 2 and we'll do -2 for the x values, 2 plug it in for x -1 so that's 2 squared is 4 -1 is 3. Again for -2 you can see we're gonna have the same answer -2 squared -1 that's again gonna be 4 because a negative times a negative is a positive when you're square rooting it. A negative number is gonna become positive, 4-1 is again 3. So maybe if you graph problems before you can start to visualize that this is going to be a parabola because these points are even. So we have a graph here and we're going to literally graph out the points x and y that we got from the index here. So we have 0, -1 so we look at 0 we go down 1. We know that's a point and check it off our list. We have 1,0 that's another point. So we go over one and we stop at 0 on the x - axis. That's another point we can check that off. We have -1, 0. Go over -1 it's another point. You can check that off, 2,3, go over 2 up 3, check that off, -2,3 again as you can see is gonna be a mirror image right across the y-axis which give us a parabola and that will show us what the graph looks like just from plotting the points we found creating the index of a function. I'm Rachel and thanks for learning with us today.

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