Tutor.com Quadratic Functions Session

Apr. 7, 2012

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Session Transcript - Math - Algebra II, 4/1/2012 3:12PM - Tutor.comSession Date: 4/1/2012 3:12PM
Length: 32.9 minute(s)
Subject: Math - Algebra II


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

James (Customer)
[00:00:00] polynomial equation [ File > http://lhh.tutor.com/SharedSessionFiles/e6f85cc8-3aba-4c85-bcb6-9cff34252261_pg4.jpg ]
[00:00:05] hello..

Michael D (Tutor)
[00:00:11] Hello.
[00:00:14] Let's get started

James (Customer)
[00:00:24] 5 and 6

Michael D (Tutor)
[00:01:20] do you mean problems 5 and 6 on the file you sent?

James (Customer)
[00:01:29] yes

Michael D (Tutor)
[00:01:48] because i only see problems 2, 3, and 4abcd
[00:02:15] did you send the correct file?

James (Customer)
[00:02:33] File Shared > pg5.jpg
[00:02:36] sry..

Michael D (Tutor)
[00:03:05] ok got it now. please give me a moment to read
[00:03:33] ok
[00:03:42] and how far did you get on problem 5?

James (Customer)
[00:04:16] I haven't started...

Michael D (Tutor)
[00:04:34] do you have any idea how to begin?

James (Customer)
[00:04:50] not quite..

Michael D (Tutor)
[00:05:09] alright
[00:05:25] do you at least understand what this question is asking?

James (Customer)
[00:06:27] yes..
[00:06:54] set 8796
[00:07:06] set R =8796

Michael D (Tutor)
[00:07:14] that would be a good start
[00:07:32] and then we will have a quadratic in the variable p
[00:07:57] good
[00:08:04] and that will equal zero
[00:09:01] and what method(s) do you know to solve this type of equation?

James (Customer)
[00:09:14] quadractic...formula...

Michael D (Tutor)
[00:09:21] good idea
[00:09:31] try that please
[00:10:50] looks like you forgot one piece
[00:11:02] the "-b" in the numerator
[00:11:08] much better
[00:11:24] now we can evaluate

James (Customer)
[00:11:56] correct?

Michael D (Tutor)
[00:12:09] so far so good

James (Customer)
[00:13:18] right?

Michael D (Tutor)
[00:13:36] so far yes
[00:13:49] it looks like you rounded to the nearest unit
[00:14:02] in each solution
[00:14:18] that may not be a good idea in the end
[00:14:29] but before we get to that ....
[00:14:52] let's determine if either or both of these solutions is any good
[00:15:21] please go back and re-read the original function
[00:15:33] paying close attention to the domain given
[00:16:16] do you understand what i am asking you look for?

James (Customer)
[00:16:24] not quite..
[00:16:47] how many..patties were sold less than 8796?

Michael D (Tutor)
[00:17:07] in the problem, next to the rule "42p-0.015p^2", they give you the interval for p over which this formula is valid
[00:17:27] p is less than or equal to 500
[00:17:39] do you se it now?

James (Customer)
[00:18:01] yes..

Michael D (Tutor)
[00:18:03] good
[00:18:14] so, only one of our solutions will work

James (Customer)
[00:18:45] ok

Michael D (Tutor)
[00:19:07] now about the "less than 8796" restriction
[00:19:39] the exact solution you got was somewhere between p=227 and p=228, right?

James (Customer)
[00:19:50] yes..
[00:20:40] ok...

Michael D (Tutor)
[00:20:45] now if you actually plug those two values for p into the function, you will see that the R(228) is actually a little bit over 8796
[00:20:52] i get 8796.24
[00:21:15] that may be important to your instructor
[00:21:34] the instructions were "less than 8796"

James (Customer)
[00:21:41] okay..I got

Michael D (Tutor)
[00:21:48] good

James (Customer)
[00:21:49] 227.9931741
[00:21:51] ...
[00:21:52] for x
[00:21:57] thats exact..
[00:22:06] so I plug that for p?

Michael D (Tutor)
[00:22:33] but, we need to round to an integer, since p is a number of items sold
[00:22:45] so, we must round down to 227

James (Customer)
[00:22:46] so 228
[00:22:52] why?

Michael D (Tutor)
[00:23:05] R(227) is below 8796
[00:23:20] R(228) is slightly over

James (Customer)
[00:23:33] ok

Michael D (Tutor)
[00:23:37] and we were explicitly told to keep it below 8796
[00:24:08] do you have any further questions about problem #5?

James (Customer)
[00:24:30] ok..so..
[00:24:39] my statement would be...
[00:25:25] Im not quite sure...what I would write for my statement

Michael D (Tutor)
[00:25:54] the number of products sold is p=227

James (Customer)
[00:26:05] ok..

Michael D (Tutor)
[00:26:44] you solved the quadratic, but only the smaller of the two solutions fit the restriction p < 500
[00:28:16] and for the good solution, we had to round down the integer below (227), because if we rounded up (to 228) the revenue R would have been above $8796
[00:28:29] got it?

James (Customer)
[00:28:48] ok..
[00:29:46] so..my final ans is 227

Michael D (Tutor)
[00:29:56] yes, i agree

James (Customer)
[00:29:59] ok

Michael D (Tutor)
[00:31:13] i am sorry, but since we have run long on this problem, i must ask you to log back in to connect to another tutor for the next problem
[00:31:49] do you have any questions on anything we went over today?

James (Customer)
[00:31:52] no

Michael D (Tutor)
[00:31:57] alright
[00:32:04] Thanks for using Tutor.com. 
[00:32:11] bye