##### Apr. 24, 2012

Session Transcript - Math - Algebra, 4/21/2012 4:31PM - Tutor.comSession Date: 4/21/2012 4:31PM
Length: 16.7 minute(s)
Subject: Math - Algebra

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

Derek (Customer)
[00:00:00] need to use Quadratic Formula to solve the equation d^2-4d-96=0

Santiago P (Tutor)
[00:00:07] HI. Welcome to tutor.com . How are you?

Derek (Customer)
[00:00:14] good how are you

Santiago P (Tutor)
[00:00:26] Fine, thanks. Let's take a look at your problem.
[00:00:54] So, you need to solve this quad equation using quadratic formula, right?

Derek (Customer)
[00:00:59] yes

Santiago P (Tutor)
[00:01:10] OK. Have you already worked on it, or you don't know how to start?

Derek (Customer)
[00:01:36] i wasnt there when they learned it but i found the formula

Santiago P (Tutor)
[00:01:49] OK. So, would you like to give it a try?

Derek (Customer)
[00:02:06] with you?

Santiago P (Tutor)
[00:02:27] Mmmm, not necessarily. If you want you can do it for yourself.

Derek (Customer)
[00:02:48] yes i would like help thou

Santiago P (Tutor)
[00:03:01] OK.
[00:03:12] I'll write the formula here, just in case.
[00:04:18] OK, this is it. We can do it if we plug the values of a, b and c, then simplify.

Derek (Customer)
[00:05:05] i was able to plug in the numbers then i got lost

Santiago P (Tutor)
[00:05:28] Where did you get lost?

Derek (Customer)
[00:06:20] trying to find out what b^2- 4ac square rooted was

Santiago P (Tutor)
[00:06:33] Oh, OK. Let me show you.
[00:06:55] Mmm, in this case, a = 1, b = -4 and c = -96. If we plug them, we get...
[00:07:56] Do you follow me so far?

Derek (Customer)
[00:08:05] yeah

Santiago P (Tutor)
[00:08:24] OK. Inside the root, (-4) squared is equal to what?

Derek (Customer)
[00:08:33] 16

Santiago P (Tutor)
[00:08:45] Great! And -4*1*(-96)?

Derek (Customer)
[00:09:45] 384

Santiago P (Tutor)
[00:10:16] Very, very good! And 16 + 384?

Derek (Customer)
[00:10:41] 400

Santiago P (Tutor)
[00:10:51] Excellent! So, it would be...
[00:11:46] OK. So, we can simplify it if we decompose that 400 into rime factors.

Derek (Customer)
[00:12:02] would it =20

Santiago P (Tutor)
[00:12:11] Great!!
[00:12:43] So, looks like all that's left is to find the two solutions, one for plus, and one for minus.

Derek (Customer)
[00:13:06] ok

Santiago P (Tutor)
[00:13:17] OK. So, would you like to give this step a try?

Derek (Customer)
[00:13:53] d=-12 and d=12?

Santiago P (Tutor)
[00:14:22] 12 is great! But are you sure of that -12?

Derek (Customer)
[00:15:02] wait it would be 8 right

Santiago P (Tutor)
[00:15:13] You got it!
[00:15:24] d=12 and d=-8. Fantastic job!

Derek (Customer)
[00:15:33] thank you

Santiago P (Tutor)
[00:15:48] Glad to have helped you. So, does this problem make sense to you now?

Derek (Customer)
[00:15:56] yes it does

Santiago P (Tutor)