# Tutor.com Linear Functions Session

##### Dec. 14, 2012

Session Transcript - Math - Algebra II, 11/30/2012 10:15PM - Tutor.comSession Date: 11/30/2012 10:15PM
Length: 53.4 minute(s)
Subject: Math - Algebra II

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

Angel (Customer)
[00:00:05] (1,4,2) -2x-y+5z=12 3x+2y-z=7 -5x+4y+2z=-17

Rebecca M (Tutor)
[00:00:11] Hello!
[00:01:23] How can I help?

Angel (Customer)
[00:02:08] Hello, i need help on this..

Rebecca M (Tutor)
[00:02:18] what are the directions?

Angel (Customer)
[00:03:01] well it gives the ordered triple number
[00:03:19] but it wants to know if it is the correct
[00:03:23] pair

Rebecca M (Tutor)
[00:03:32] Do you know how to check it?

Angel (Customer)
[00:03:52] not entirely sure

Rebecca M (Tutor)
[00:04:42] So we plug 1 in for x, 4 in for y and 2 in for z and see if it = 12 in the first equation

Angel (Customer)
[00:05:14] okie dokie then

Rebecca M (Tutor)
[00:05:09] -2(1) - (4) + 5(2) = ?

Angel (Customer)
[00:06:06] 39?
[00:07:18] oops i mean -4

Rebecca M (Tutor)
[00:07:18] so close!

Angel (Customer)
[00:07:48] 4

Rebecca M (Tutor)
[00:07:46] you got it!

Angel (Customer)
[00:08:22] awesome i feel somewhat smarter

Rebecca M (Tutor)
[00:08:19]
[00:08:24] so it doesn't equal 12
[00:08:27] it equal 4

Angel (Customer)
[00:08:36] no

Rebecca M (Tutor)
[00:08:31] so it's not a solution

Angel (Customer)
[00:08:46] ok
[00:09:10] would that apply for the other equations too

Rebecca M (Tutor)
[00:09:14] yes

Angel (Customer)
[00:09:36] ok then also i got one more

Rebecca M (Tutor)
[00:09:30] is it a system or do we have to check each one/

Angel (Customer)
[00:10:05] its...
[00:10:39] the same kind of problem but instead i have to find out what the ordered triple is

Rebecca M (Tutor)
[00:10:44] ooooo...so fun!

Angel (Customer)
[00:11:00] i know right
[00:12:13] 2x-4y+3z=1 6x+2y+10z=19 - 2x+5y-2z=

Rebecca M (Tutor)
[00:12:21] want to write it on the whiteboard?
[00:13:53] beautiful!
[00:14:06] Any idea where to start? Do you have a battle plan?

Angel (Customer)
[00:14:37] from what i know you find out which variable to get rid of first

Rebecca M (Tutor)
[00:14:47] correct
[00:14:53] any favorites?

Angel (Customer)
[00:15:27] i think x

Rebecca M (Tutor)
[00:15:28] ok let's get rid of x
[00:15:36] do you know how to do that?

Angel (Customer)
[00:16:52] lemme see, you have to multiply by -3

Rebecca M (Tutor)
[00:17:00] to use the 1st two equations?

Angel (Customer)
[00:17:17] yes

Rebecca M (Tutor)
[00:17:17] go for it
[00:20:13] -10y -z = 16
[00:20:17] that's what I got
[00:20:27] I mean

Angel (Customer)
[00:20:37] -10y+-z=16

Rebecca M (Tutor)
[00:20:37] -10y + z = 16

Angel (Customer)
[00:21:19] THEN..

Rebecca M (Tutor)
[00:22:08] I would multiply the bottom one by -3
[00:22:18] and add the 2nd and 3rd together
[00:24:34] great!

Angel (Customer)
[00:24:54] yeah!

Rebecca M (Tutor)
[00:25:17] now I would mulitply that blue equation by -16 to get rid of y

Angel (Customer)
[00:26:23] :0
[00:26:42] brb lemme get my calculator

Rebecca M (Tutor)
[00:26:39] ok
[00:26:42] good idea

Angel (Customer)
[00:27:05] im back

Rebecca M (Tutor)
[00:27:02]
[00:30:11] it doesn't come out to a whole number

Angel (Customer)
[00:30:44] no it doesnt did i do something wrong

Rebecca M (Tutor)
[00:30:56] let me check, this might take a minute, do you have time?

Angel (Customer)
[00:31:11] yes

Rebecca M (Tutor)
[00:31:17] double check that the problem is written correctly

Angel (Customer)
[00:32:54] oh i think i see whqt went wrong

Rebecca M (Tutor)
[00:32:57] ok what do you see?

Angel (Customer)
[00:33:24] its supposed to be -z

Rebecca M (Tutor)
[00:33:24] where?

Angel (Customer)
[00:33:36] for the blue equation

Rebecca M (Tutor)
[00:33:39] no because
[00:33:50] -9z + 10z = z

Angel (Customer)
[00:34:37] oh /:0 ok then

Rebecca M (Tutor)
[00:34:49] But your original problem is written down correctly?

Angel (Customer)
[00:35:09] ok then

Rebecca M (Tutor)
[00:36:03] I don't see anything wrong with what you did.
[00:36:12] You're sure the problem is written down correctly?

Angel (Customer)
[00:36:28] im positive

Rebecca M (Tutor)
[00:37:23] so y = -243/147
[00:37:30] that's just ugly
[00:37:33] sorry

Angel (Customer)
[00:37:50] thats ok

Rebecca M (Tutor)
[00:37:56] now let's find z

Angel (Customer)
[00:38:29] ok

Rebecca M (Tutor)
[00:38:41] Let's subtract the 1st and 3rd equations
[00:38:48] and we'll get
[00:39:05] -y + 5z = -1
[00:39:11] ok?

Angel (Customer)
[00:39:26] okie dokie

Rebecca M (Tutor)
[00:40:28] let's multiply the second one by -5
[00:43:18] let's just leave it as 79/49

Angel (Customer)
[00:43:48] in that case 1.61
[00:45:14] in my book in the back they have -1/2, 1, 2
[00:45:27] for that problem

Rebecca M (Tutor)
[00:45:20] ugh

Angel (Customer)
[00:45:55] im really sorry

Rebecca M (Tutor)
[00:47:01] I don't know what to tell you
[00:47:05] I can't find the problem
[00:47:25] one more sec, if you have time

Angel (Customer)
[00:47:47] i do

Rebecca M (Tutor)
[00:47:53] for the first equation...
[00:48:04] 2x + 4y + 3z =1
[00:48:44] we get 2(-1/2) + 4(1) +3(2)
[00:48:53] that equals -1 +4 +6
[00:48:59] which equals 9 not 1

Angel (Customer)
[00:49:25] what da heck

Rebecca M (Tutor)
[00:49:20]
[00:49:45] it works for the second equation
[00:50:07] but not the 3rd one

Angel (Customer)
[00:50:33] oh i see

Rebecca M (Tutor)
[00:50:51] what do you see?

Angel (Customer)
[00:52:13] oh i gots to go

Rebecca M (Tutor)
[00:52:11] bummer
[00:52:17] ok, well good luck
[00:52:31] sorry i couldn't be more help

Angel (Customer)
[00:52:51] dont sweat it

Rebecca M (Tutor)
[00:52:46]

Angel (Customer)
[00:53:03] thanks for the help though

Rebecca M (Tutor)
[00:52:57] ok
[00:53:00] good night

Angel (Customer)
[00:53:19] good night