Tutor.com Quadratic Equations Session

Apr. 8, 2012

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Session Transcript - Math - Algebra, 3/30/2012 3:32PM - Tutor.comSession Date: 3/30/2012 3:32PM
Length: 9.7 minute(s)
Subject: Math - Algebra


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

Shane (Customer)
[00:00:00] Find the dimensions of the triangle with an area of 30 square centimeters!i don't know how to do this! D:
[00:00:04] hello

Michael L (Tutor)
[00:00:06] Welcome to Tutor.com ! Let's get started.

Shane (Customer)
[00:00:08] Ok

Michael L (Tutor)
[00:00:27] Ok, so you're given an area and asked to work backwards. I think we can work with this.
[00:00:35] What is the area of a triangle in general?

Shane (Customer)
[00:00:48] ...I don't understand...

Michael L (Tutor)
[00:00:54] Ok, sure.
[00:01:12] How would you find the area of that triangle?

Shane (Customer)
[00:01:12] 1/2BH
[00:01:14] ?

Michael L (Tutor)
[00:01:20] Good! Let's use that.
[00:01:31] One quick clarification. Is x the length of the whole base?

Shane (Customer)
[00:01:42] Yes
[00:01:50] And the X+17 is the Height

Michael L (Tutor)
[00:01:57] Ok, let's use our formula then.
[00:02:11] A = (1/2)BH, so simply substitute in exactly what you just told me.

Shane (Customer)
[00:02:21] 1/2(x)(x+17)?

Michael L (Tutor)
[00:02:34] Good! And we also know the other side of the equation. It was given to us.

Shane (Customer)
[00:02:52] 30=1/2(x)(x+17)

Michael L (Tutor)
[00:03:01] Good! If you solve that, you're done.

Shane (Customer)
[00:03:06] Ok

Michael L (Tutor)
[00:03:17] Might I make a small recommenation?
[00:03:21] recommendation*

Shane (Customer)
[00:03:28] Ok

Michael L (Tutor)
[00:03:33] Multiply by 2 first to get rid of fractions.

Shane (Customer)
[00:03:54] 60=X(X+17)?

Michael L (Tutor)
[00:04:07] good! Do you know how to solve it?

Shane (Customer)
[00:04:13] so 60 = x^2 + 17
[00:04:20] subtract 17 from both sides

Michael L (Tutor)
[00:04:26] 60 = x^2 + 17x, careful

Shane (Customer)
[00:04:30] O thanks

Michael L (Tutor)
[00:04:49] So we may want to subtract something besides the 17.
[00:04:54] err, 17x now.

Shane (Customer)
[00:05:08] I'm following...

Michael L (Tutor)
[00:05:25] Ok, for most quadratic equations, we want to get one side equal to 0 first.
[00:05:32] Then we can factor or use the quadratic formula.

Shane (Customer)
[00:05:32] 0=x^2+17-60?
[00:05:40] 17x*

Michael L (Tutor)
[00:05:44] Good!
[00:05:55] What do you want to try from here?

Shane (Customer)
[00:06:34] (x+20)(x-3)?

Michael L (Tutor)
[00:06:39] Very good!

Shane (Customer)
[00:07:04] 0= (x+20)(x-3)
[00:07:05] so
[00:07:15] X+20 = 0
[00:07:16] or
[00:07:24] x-3 = 0
[00:07:36] x = -20, or 3

Michael L (Tutor)
[00:07:42] So far so good!

Shane (Customer)
[00:07:46] since it can't be negative then it has to be the 3
[00:07:50] X=3?

Michael L (Tutor)
[00:08:03] Ok, good! Let's make sure we've answered the original question.

Shane (Customer)
[00:08:16] 30= 1/2(3)(3+17)

Michael L (Tutor)
[00:08:22] It wants the dimensions of the triangle, so what is the base and the height?

Shane (Customer)
[00:08:35] b=3, h=20

Michael L (Tutor)
[00:08:41] Good!
[00:08:46] Do you have any questions about anything we went over today?

Shane (Customer)
[00:08:59] No, it seems simple now, thanks so much!

Michael L (Tutor)
[00:09:04] You're welcome!

Shane (Customer)
[00:09:06]

Michael L (Tutor)
[00:09:08] Thanks for using Tutor.com. Please fill out the survey as you leave so we can learn how we can better help you in the future!
[00:09:23] Bye now!

Shane (Customer)
[00:09:34] Bye