# Tutor.com Linear Functions Session

##### Sep. 20, 2012

Session Transcript - Math - Algebra II, 9/10/2012 10:42PM - Tutor.comSession Date: 9/10/2012 10:42PM
Length: 19.5 minute(s)
Subject: Math - Algebra II

System Message
[00:00:00] *** Please note: All sessions are recorded for quality control. ***

Victoria (Customer)
[00:00:00] the question is.. find the point slope form of the equation of the line pasin through the points (-6,-4) (2,-5)

Sam B (Tutor)
[00:00:19] Welcome to Tutor.com ! Let's get started.
[00:00:49] Do you happen to remember what "point-slope" form looks like when writing a linear equation?

Victoria (Customer)
[00:01:20] is it something like x1 and y1

Sam B (Tutor)
[00:01:47] You're right, the point-slope form does incorporate x1 and y1 in the equation.
[00:01:55] What do these represent?

Victoria (Customer)
[00:02:07] the x and y int

Sam B (Tutor)
[00:02:38] Not quite, it's actually just one of the points on the line itself, so we could use either (-6,-4) or (2,-5).

Victoria (Customer)
[00:02:48] oh okay

Sam B (Tutor)
[00:02:51] But first we need to find our slope.
[00:03:03] Do you know how to find the slope of a line when given two points on that line?

Victoria (Customer)
[00:03:26] x1-x2 /y1-y2
[00:03:29] ?

Sam B (Tutor)
[00:04:31] You're very close. Do you happen to remember the phrase "rise over run" when finding the slope?

Victoria (Customer)
[00:05:05] yes

Sam B (Tutor)
[00:05:40] Cool! So would x be "rise" or "run" when we look at a graph and its axis?

Victoria (Customer)
[00:05:59] run
[00:06:23] 3x would be up one over 3

Sam B (Tutor)
[00:06:53] Well, you're right that x is our "run", so would it be on the top or bottom of our fraction?

Victoria (Customer)
[00:07:32] bottom.?

Sam B (Tutor)
[00:07:56] Correct! Since we're talking about "rise over run", that's another way of saying "rise divided by run", so it would be on the bottom.
[00:08:07] And if that's the case, our y variable would be on the top, right?

Victoria (Customer)
[00:08:33] ya

Sam B (Tutor)
[00:08:46] Great, so the equation for slope would look something like this:
[00:09:53] And m would be our slope.

Victoria (Customer)
[00:10:06] ok

Sam B (Tutor)
[00:10:39] Awesome!
[00:10:43] Our slope would be -1/8
[00:10:58] Now all we need is to put it in the point-slope form equation, which looks like this:

Victoria (Customer)
[00:11:04] okay

Sam B (Tutor)
[00:11:55] And "y" and "x" are just variables, so we don't need to plug anything in for them.
[00:12:15] Now we have everything we need! Could you plug the numbers in for me?
[00:13:06] You can type it out if you like.
[00:14:42] Well, if we substitute numbers in for our "y" and "x", would this be a linear equation?
[00:14:58] We actually only need to put numbers in for our y1 and x1.

Victoria (Customer)
[00:15:09] ohok

Sam B (Tutor)
[00:16:02] Perfect! Now all we need to do is simplify.
[00:16:14] As in, change the double negatives into positives

Victoria (Customer)
[00:17:28] okay

Sam B (Tutor)
[00:18:26] I assume you meant to put "+" instead a "=" at the end, so you're exactly right! Great job.

Victoria (Customer)
[00:18:40] oh yea1

Sam B (Tutor)
[00:18:58] And that is how we write equations in point-slope form! Do you have any questions about anything we went over today?

Victoria (Customer)
[00:19:04] nope not at all

Sam B (Tutor)
[00:19:08] Great!
[00:19:14] Thanks for using Tutor.com.Â Please fill out the survey as you leave so we can learn how we can better help you in the future!Â
[00:19:22] Have a great day.

Victoria (Customer)
[00:19:25] ou too!