Tutor.com Linear Equations Session

Dec. 4, 2012

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Session Transcript - Math - Algebra, 12/1/2012 1:17PM - Tutor.comSession Date: 12/1/2012 1:17PM
Length: 55.7 minute(s)
Subject: Math - Algebra


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

Sahil (Customer)
[00:00:00] can we practice finding the slope of a line? using graphs,tables,and equations please? (can u make up the problems pls?)
[00:00:15] hi

Jack K (Tutor)
[00:00:20] Hello! My name is Jack. How are you today?

Sahil (Customer)
[00:00:56] im fine how are you?

Jack K (Tutor)
[00:01:36] Great! Let's get started. So, what exactly are you wanting to practice with?

Sahil (Customer)
[00:01:53] Finding the slope of a line using a graph, first

Jack K (Tutor)
[00:03:24] Okay, we can do that.

Sahil (Customer)
[00:03:29] k

Jack K (Tutor)
[00:03:49] Hold on one moment, let me see if I can find a few examples for us.

Sahil (Customer)
[00:03:52] k

Jack K (Tutor)
[00:05:54] Alright, I'll just try drawing one on the board

Sahil (Customer)
[00:06:08] k

Jack K (Tutor)
[00:07:55] It isn't exactly to scale. Is this similar to what problems of yours look like?

Sahil (Customer)
[00:08:09] yes sir, but can u draw all the numbers please?

Jack K (Tutor)
[00:08:24] Of course
[00:09:15] Okay, how would we go about finding the slope of this line?

Sahil (Customer)
[00:09:30] is the slope 2?

Jack K (Tutor)
[00:10:01] Very Close! Think about the direction the line is going

Sahil (Customer)
[00:10:05] -2

Jack K (Tutor)
[00:10:14] Yes! Well done.

Sahil (Customer)
[00:10:17] (:
[00:10:24] can we do one using a graph pls?

Jack K (Tutor)
[00:10:54] I'm sorry, I'm not sure what you mean by that.

Sahil (Customer)
[00:10:59] i mean table*
[00:11:01] sorry
[00:11:02] lol

Jack K (Tutor)
[00:11:22] Ahh, yes! we can do that
[00:13:02] What is the slope?

Sahil (Customer)
[00:14:21] well i know that the bottom number is 1

Jack K (Tutor)
[00:15:36] Okay, so you're using the slope formula. Good! So which two numbers did you pick?

Sahil (Customer)
[00:15:48] im not sure about y
[00:16:06] is y 1/2?

Jack K (Tutor)
[00:16:34] Yes!

Sahil (Customer)
[00:16:48] so the slope is 1/2

Jack K (Tutor)
[00:17:04] Exactly! Well done.

Sahil (Customer)
[00:17:13] and the equation is y=1/2x plus -2
[00:17:32] i mean plus -3

Jack K (Tutor)
[00:17:59] Right! You seem to understand this stuff pretty well

Sahil (Customer)
[00:18:09] can we do one with an equation pelase?

Jack K (Tutor)
[00:18:23] Of course
[00:19:21] What would the slope be in this case?

Sahil (Customer)
[00:19:26] 3
[00:19:32] x

Jack K (Tutor)
[00:19:49] Ahh, be careful

Sahil (Customer)
[00:20:10] oh is it -2 1/3x
[00:20:26] or do we have to do the adding process

Jack K (Tutor)
[00:20:57] In order to find the slope, we need to put the equation in y=mx+b form

Sahil (Customer)
[00:21:00] oh k
[00:21:11] so first we subtract 2y from -7
[00:22:23] next do we didive by 3x?
[00:22:27] divide*

Jack K (Tutor)
[00:22:57] Well, what we want to do is get y alone
[00:23:07] These two equations are the same

Sahil (Customer)
[00:23:29] so we do -9 instead of -7?

Jack K (Tutor)
[00:24:13] No, you can't subtract 2y from -7 like that, because only one of those has a variable.
[00:24:27] What we need to do is get y on its on on one side

Sahil (Customer)
[00:25:03] -10

Jack K (Tutor)
[00:25:04] Try subtracting 3x
[00:25:25] No, you can't add and subtract a constant and a variable
[00:25:45] This is impossible, since we don't know what x is
[00:25:55] instead we just need to rewrite it
[00:26:12] Does that make sense?

Sahil (Customer)
[00:26:11] oh i see
[00:26:15] yes sir

Jack K (Tutor)
[00:26:28] Good! So what's next?

Sahil (Customer)
[00:26:35] divide by 2

Jack K (Tutor)
[00:26:45] Right! What do we get?

Sahil (Customer)
[00:26:53] -3.5
[00:26:59] or - 3 1/2

Jack K (Tutor)
[00:27:31] Okay, so in y=mx+b, which part is -3.5?

Sahil (Customer)
[00:28:16] b

Jack K (Tutor)
[00:28:43] Right! Which means it is the y-intercept, not the slope. What is mx in this case?

Sahil (Customer)
[00:28:55] the slope

Jack K (Tutor)
[00:29:08] Yes! So for this equation, what is the slope?

Sahil (Customer)
[00:29:18] 3x
[00:29:28] ?

Jack K (Tutor)
[00:30:05] Well, we need to look at it once the equation is completely simplified. What do you get after you divide by 2?

Sahil (Customer)
[00:31:00] which equation are we looking at???

Jack K (Tutor)
[00:31:12] Yes.

Sahil (Customer)
[00:31:18] k

Jack K (Tutor)
[00:31:23] We are solving for y by dividing by 2

Sahil (Customer)
[00:31:26] -3.5

Jack K (Tutor)
[00:32:03] Okay, that's one part. What else do we get?

Sahil (Customer)
[00:32:07] -3x

Jack K (Tutor)
[00:32:37] We must divide each part of the equation by 2
[00:33:00] so -3.5 is -7/2

Sahil (Customer)
[00:33:12] y=1.5x-3.5

Jack K (Tutor)
[00:33:48] Very Close! that 3x was also negative before we divided by 2
[00:33:57] remember that*

Sahil (Customer)
[00:34:08] y=-1.5x-3.5

Jack K (Tutor)
[00:34:19] Yes! So what is the slope?

Sahil (Customer)
[00:34:26] -1.5
[00:34:28] x
[00:34:38] can we do one last one like this pls?

Jack K (Tutor)
[00:35:09] Yes. Remember that the slope for this type of equation is going to be a number.

Sahil (Customer)
[00:35:21] k

Jack K (Tutor)
[00:35:25] the slope is just m in y=mx+b, you dont need to add x

Sahil (Customer)
[00:35:58] k

Jack K (Tutor)
[00:36:19] So what is the slope of this equation?

Sahil (Customer)
[00:36:35] -8?

Jack K (Tutor)
[00:37:14] Not quite. How do we want to solve this problem?

Sahil (Customer)
[00:37:32] multiply 2 to 4
[00:37:55] or to b sorry

Jack K (Tutor)
[00:38:16] Well, that would give us x all alone, but we want to solve for y
[00:38:27] and that is supposed to by a 6, sorry

Sahil (Customer)
[00:38:44] oh okay

Jack K (Tutor)
[00:38:56] So how do we solve for y?

Sahil (Customer)
[00:39:02] 2*6?
[00:39:14] or 6/4

Jack K (Tutor)
[00:40:02] Well, what we have here is an x term on one side, and a y term and a constant on the other. We want the y term to be alone, so which part do we want to move first?

Sahil (Customer)
[00:40:10] the x
[00:40:17] so we do 6*2

Jack K (Tutor)
[00:40:44] We could do that, but then we would have to move the y. its easier to do this
[00:41:17] what does doing that give us?

Sahil (Customer)
[00:41:23] -12?

Jack K (Tutor)
[00:42:22] Not quite. Remember, we are subtracting 6 from both sides

Sahil (Customer)
[00:42:32] -4

Jack K (Tutor)
[00:43:07] Where are you subtracting?
[00:43:39] Remember, only constants and other constants work like that
[00:43:50] rewrite the equation like I did in the last problem

Sahil (Customer)
[00:43:52] so it would be

Jack K (Tutor)
[00:44:12] Yes!
[00:44:24] Well done. So, what's the next step?

Sahil (Customer)
[00:44:40] multiply both sides by 2?

Jack K (Tutor)
[00:44:58] We want to get y by itself
[00:45:08] So we need to remover the 4 from the right side
[00:45:12] how do we do that?

Sahil (Customer)
[00:45:29] dvide
[00:45:33] divide

Jack K (Tutor)
[00:45:40] Yes! and what do we get?

Sahil (Customer)
[00:45:52] -1.5

Jack K (Tutor)
[00:46:18] That's one part. Write out the whole equation after dividing
[00:47:00] Or you can type it into chat, if you prefer

Sahil (Customer)
[00:47:17] y=x/2-1.5?

Jack K (Tutor)
[00:47:39] You have to remember to multiply everything by 4

Sahil (Customer)
[00:49:02] is this right>?

Jack K (Tutor)
[00:49:34] That is closer. However, we are dividing x by 4, so the part on the bottom should get bigger, not smaller

Sahil (Customer)
[00:50:08] i thought it was only 4????

Jack K (Tutor)
[00:50:35] We are dividing by 4, which is the same as multiplying by 1/4

Sahil (Customer)
[00:50:54] 2/4=0.5

Jack K (Tutor)
[00:51:38] Right, but that is part of a fraction. originally we had 1/2*x, or x/2
[00:51:48] and we are multiplying by 1/4

Sahil (Customer)
[00:51:50] oh i see
[00:52:07] so is it y=1/2x-1.5?\

Jack K (Tutor)
[00:52:45] Let me write it a different way, maybe it will make more sense
[00:53:21] Then we divide by 4, or multiply by 1/4
[00:53:55] So what is 1/4*1/2?

Sahil (Customer)
[00:54:03] 1/8

Jack K (Tutor)
[00:54:22] Yes! Well done. Does that make sense?

Sahil (Customer)
[00:54:27] yes
[00:54:35] can we do one last one please

Jack K (Tutor)
[00:55:37] I'm afraid That I have to end here. Try finding some problems in your book, or connecting with another tutor may help also