Tutor.com Quadratic Equations Session

May. 30, 2012

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Session Transcript - Math - Algebra, 5/23/2012 9:47PM - Tutor.comSession Date: 5/23/2012 9:47PM
Length: 19.7 minute(s)
Subject: Math - Algebra


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

Brandi (Customer)
[00:00:00] Solve each equation with the quadratic forumla.

Sara M (Tutor)
[00:00:09] Welcome to Tutor.com !

Brandi (Customer)
[00:00:26] thanks!

Sara M (Tutor)
[00:00:45] Let's take a look at your problem.
[00:00:59] First, we need to get this into standard form. Can you tell me how we would do that?

Brandi (Customer)
[00:01:24] No /: That's why i need help lol. I know how to do it if its equal to zero but its not.. /:

Sara M (Tutor)
[00:01:34] Okay.
[00:01:42] We just need to cancel the n. How would we do that?

Brandi (Customer)
[00:02:02] oh subtract n from both sides! so it would just be 10n - 19?

Sara M (Tutor)
[00:02:11] Almost!
[00:02:25] We do subtract the n, but we can't combine the 10n^2 and -n because they're not like terms.
[00:02:29] We would leave it like this...
[00:02:59] We can only combine terms that have the same variable with the same exponent on that variable.

Brandi (Customer)
[00:03:05] oh that makes sense!

Sara M (Tutor)
[00:03:09] Great!
[00:03:12] What would we do next?

Brandi (Customer)
[00:03:53] plug it into the formula!

Sara M (Tutor)
[00:04:00] Right
[00:04:40] What are a, b and c here?

Brandi (Customer)
[00:05:00] a is 10 n squared, b is - n and c is -19!
[00:05:02] i have a question!

Sara M (Tutor)
[00:05:35] Actually, we just use the numbers, not the n's a is 10, b is -1 and c is -19. But you have the right idea. What's your question?

Brandi (Customer)
[00:06:41] oh right! and say that the - 1 wasnt there, the problem just had 10n squared - 19 = 0. there was no b. would you put in a zero for b or 1?

Sara M (Tutor)
[00:07:14] You could, but then it wouldn't be quadratic, so you could just solve for n directly. Add 19, and divide by 10
[00:07:24] sorry!
[00:07:34] I forgot it was 10n^2.
[00:07:45] You could solve it using the quadratic and put 0 in there, yes.
[00:07:54] There is another way to solve, but that would work.
[00:08:13] Can you solve for n here and tell me what we get?

Brandi (Customer)
[00:08:44] yes! it may take a sec. can i do it on paper and tell you what i get? it takes forever to write on here. lol

Sara M (Tutor)
[00:08:55] Sure, no problem!

Brandi (Customer)
[00:08:58] thanks!

Sara M (Tutor)
[00:09:06] If you have problems, we can go over it together on the board.

Brandi (Customer)
[00:09:41] okay! and since the formula is -b and b is negative in this problem would it stay negative or go positive? i know a negative plus a negative is a postive i just am not sure if its different here

Sara M (Tutor)
[00:10:08] We would do -(-1) here. So, it would be +1. Does that make sense?

Brandi (Customer)
[00:10:22] yes ma'am!

Sara M (Tutor)
[00:12:01] I'm working on this...

Brandi (Customer)
[00:12:16] me too! did you get a decimal for the answer?

Sara M (Tutor)
[00:12:23] That automatically comes up when I stop typing for a bit. Sorry
[00:12:32] Let me convert mine to decimal. One moment.

Brandi (Customer)
[00:12:34] Lol it's okay!! :P It's cool!
[00:12:36] okay!

Sara M (Tutor)
[00:12:42] There should be two answers here.

Brandi (Customer)
[00:12:47] yep!
[00:13:04] -2.66 and 2.86

Sara M (Tutor)
[00:13:17] Hm...that's not what I got.
[00:13:30] Let's go over it together on the board. I can write it if you like

Brandi (Customer)
[00:13:37] ok!

Sara M (Tutor)
[00:14:27] Does that look like what you have for the set up?

Brandi (Customer)
[00:14:39] yes! P

Sara M (Tutor)
[00:14:45] Great! Next step...
[00:14:51] -(-1) give us +1.
[00:15:03] What's (-1) squared?

Brandi (Customer)
[00:15:19] postive 1!

Sara M (Tutor)
[00:15:26] Yes!
[00:15:32] And 4 times 10 times -19?

Brandi (Customer)
[00:15:51] -760 but it turns to positive since its -4!
[00:15:52] right?

Sara M (Tutor)
[00:16:07] Good!
[00:16:21] What's 1 + 760?

Brandi (Customer)
[00:16:32] 761!

Sara M (Tutor)
[00:16:58] I think I see what your problem was
[00:17:11] I think you divided by 10 instead of 20.
[00:17:17] I just realized that...

Brandi (Customer)
[00:17:24] Oh dang i did!
[00:17:30] Haha I dont even know where i got that from!

Sara M (Tutor)
[00:17:52] It was 2(10) at the beginning, and you probably just forgot it was 2 times 10, and just divided by 10.
[00:18:02] You got the answer right if you divided by 20 instead

Brandi (Customer)
[00:18:19] woohoo!! haha

Sara M (Tutor)
[00:18:34] So, basically, just divide both of your answers by 2, and you have it

Brandi (Customer)
[00:18:54] okay! thanks so much!

Sara M (Tutor)
[00:18:59] You're welcome!
[00:19:05] Thanks for using Tutor.com . Please take a minute to complete the session survey, and come back if you need more help in the future
[00:19:09] Have a good night!

Brandi (Customer)
[00:19:16] you too! you were added to my favorites! !:
[00:19:18] *

Sara M (Tutor)
[00:19:23] Thank you so much!
[00:19:28] Bye

Brandi (Customer)
[00:19:32] bye!