Tutor.com Linear Equations Session

Feb. 17, 2014

Session Transcript - Math - Algebra, 2/10/2014 8:02PM - Tutor.comSession Date: 2/10/2014 8:02PM
Length: 36.2 minute(s)
Subject: Math - Algebra

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Guest (Customer)
[00:00:02] /

George M (Tutor)

Guest (Customer)
[00:00:52] find xandy for
[00:01:01] 10x-12y=60

George M (Tutor)
[00:01:16] Are you given any other directions or information with this problem?

Guest (Customer)
[00:01:26] no

George M (Tutor)
[00:01:54] hmm ok, are you sure you're not given another equation or some other information?

Guest (Customer)
[00:02:35] no
[00:02:46] am i suppose 2 use y=mx+b?

George M (Tutor)
[00:03:22] Hmm I'm not sure if you're not given any other info, if It's alright with you I'm going to transfer you to another tutor who may be able to better assist you with this question

Guest (Customer)
[00:04:27] ok
[00:04:32] but it is simple
[00:04:36] simply

System Message
[00:04:58] *** The session has been transferred. ***

Zach D (Tutor)
[00:05:12] Welcome to Tutor.com ! Let's get started.

Guest (Customer)

Zach D (Tutor)
[00:05:59] I see it: 10x-12y=60
[00:06:18] And you are trying to solve for x and y, correct?

Guest (Customer)
[00:06:46] ye
[00:06:48] yes

Zach D (Tutor)
[00:07:15] Were there any other directions or perhaps another equation with this one?

Guest (Customer)
[00:07:50] yes
[00:08:01] what other dierections were there suppose to be?

Zach D (Tutor)
[00:08:33] Well, when you have two variables (x and y), you need two equations to solve for them.

Guest (Customer)
[00:08:57] it says find the x and y intercepts

Zach D (Tutor)
[00:09:04] Oh OK!
[00:09:28] Do you know what those are?

Guest (Customer)
[00:09:36] no

Zach D (Tutor)
[00:10:00] That's OK. The intercepts are the points where a line crosses the x-axis and the y-axis.
[00:10:06] Does that make sense>
[00:10:07] ?

Guest (Customer)
[00:11:14] yes

Zach D (Tutor)
[00:11:33] Let me draw an x-y plane on the white board.

Guest (Customer)
[00:11:54] ok

Zach D (Tutor)
[00:12:22] So what can you tell me about the x axis? Such as, what are some points on the x axis?

Guest (Customer)
[00:13:32] they intesect

Zach D (Tutor)
[00:13:59] Right, the axes intersect at the point (0,0) also called the origin.

Guest (Customer)
[00:14:25] 0,0

Zach D (Tutor)
[00:14:57] Right. What about the point (3,0)? Would that be on the x-axis?

Guest (Customer)
[00:15:27] yes

Zach D (Tutor)
[00:15:40] Good. So what do those two points have in common?

Guest (Customer)
[00:16:28] both have 0

Zach D (Tutor)
[00:16:50] Right. Both have the second coordinate (the y coordinate) equal to zero.
[00:17:08] In fact, all points on the x-axis have a y-coordinate equal to zero.
[00:17:43] So if the x-intercept is the point where the line goes through the x-axis, what do you think we should do next?

Guest (Customer)
[00:18:06] plug the points in

Zach D (Tutor)
[00:18:33] Close! Let's take the original equation and substitute 0 for y.
[00:18:46] Would you like to try?

Guest (Customer)
[00:19:05] why do i sue 0?

Zach D (Tutor)
[00:19:39] The x-intercept is a point on the x-axis. And we found earlier that all points on the x-axis have y=0.

Guest (Customer)
[00:20:38] how did u get 3?

Zach D (Tutor)
[00:20:58] That was just an example of a point on the x-axis. Sorry if that confused you.

Guest (Customer)
[00:22:13] so using my eqation what do i do

Zach D (Tutor)
[00:22:35] To find the x-intercept, substitute 0 for y and solve for x.
[00:22:42] Would you like to try?

Guest (Customer)
[00:23:39] why is 0 used

Zach D (Tutor)
[00:24:25] Zero is used for y in this case because all points on the x-axis (including the x-intercept) have a y-value equal to 0.

Guest (Customer)
[00:25:01] u got that infomation by using 10x-12y=60

Zach D (Tutor)
[00:25:44] No. We still haven't found the intercepts yet. We'll find the x-intercept by substituting 0 for y and solving for x.
[00:25:50] Would you like me to show you?

Guest (Customer)
[00:26:00] YES

Zach D (Tutor)
[00:26:07] OK
[00:27:39] So when y=0, x=6. Our x-intercept is (0,6).
[00:27:51] Does that make sense?
[00:28:25] Sorry. (6,0)\
[00:28:33] I reversed the numbers.

Guest (Customer)
[00:28:50] yes
[00:29:05] do i use 0 for all eqations like this?

Zach D (Tutor)
[00:29:44] To find the intercepts, yes. We found the x intercept for substituting 0 for y. What do you think we should do to find the y intercept?

Guest (Customer)
[00:30:16] plug 6 in

Zach D (Tutor)
[00:30:42] Not quite. You'll still use zero, but this time substitute zero for x.
[00:30:49] And solve for y.

Guest (Customer)
[00:31:37] so do 10(0)

Zach D (Tutor)
[00:31:44] Yes.
[00:32:12] Then what?

Guest (Customer)
[00:32:39] so can u write the eatuion on the borad again so ic do it

Zach D (Tutor)
[00:32:42] Sure
[00:34:32] Almost.
[00:34:38] Remember that was a negative 12.

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Zach D (Tutor)
[00:37:04] Are you there?