Tutor.com Quadratic Functions Session

Sep. 24, 2012

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Session Transcript - Math - Algebra II, 9/18/2012 2:24PM - Tutor.comSession Date: 9/18/2012 2:24PM
Length: 31.2 minute(s)
Subject: Math - Algebra II


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

shanice (Customer)
[00:00:00] hi :)

Holly F (Tutor)
[00:00:27] Hi! How may I help you?

shanice (Customer)
[00:00:42] 0=2x^2+7x-3

Holly F (Tutor)
[00:01:16] What are the instructions, please?

shanice (Customer)
[00:01:27] i need to factor

Holly F (Tutor)
[00:01:44] Okay. Can you tell me your ideas on what to do?

shanice (Customer)
[00:02:45] oh, sorry
[00:02:54] i wrote it wrong...

Holly F (Tutor)
[00:03:01] okay

shanice (Customer)
[00:03:15] -2x^2
[00:03:24] instead of positive

Holly F (Tutor)
[00:03:59] okay tell what you know about how to factor this.

shanice (Customer)
[00:04:48] i need to ask myself...
[00:05:07] what multiplies to get 6, and adds to get 7
[00:05:15] ...is that right?

Holly F (Tutor)
[00:05:44] yes

shanice (Customer)
[00:06:06] is it
[00:06:10] -6 and -1
[00:06:12] ?

Holly F (Tutor)
[00:06:30] does -6 plus -1 equal 7?
[00:06:35] you are close.

shanice (Customer)
[00:07:12] no..
[00:07:27] 6 + 1
[00:07:29] ?

Holly F (Tutor)
[00:07:33] there you go

shanice (Customer)
[00:08:17] im not sure about the next step

Holly F (Tutor)
[00:08:33] now, we are going to rewrite 7x as 6x + 1x. then we will complete the problem using factoring by grouping
[00:08:54] do you remember factoring by grouping?

shanice (Customer)
[00:10:02] no ?

Holly F (Tutor)
[00:10:39] okay. let me write what we have so far on the board and i will guide you through it.
[00:12:47] okay. the reason we wanted to find the numbers that muliply together to give us 6 and add to 7 is to transform the equation into something that is factorable by grouping.
[00:13:21] now we want to group the first two terms together and the second two terms together

shanice (Customer)
[00:13:28] oh okay, i see

Holly F (Tutor)
[00:14:11] now, we want to factor something out of each group so that the leftovers are the SAME in each group
[00:14:24] what can we factor out of the first group?

shanice (Customer)
[00:15:34] 2x?

Holly F (Tutor)
[00:16:15] good
[00:16:36] are the expressions in the () the same? we want them to be the same.

shanice (Customer)
[00:16:51] no..
[00:16:56] ones negative

Holly F (Tutor)
[00:17:34] right. but we can make them the same. what can we factor out of the first set or the second set of () to make them the same?
[00:19:10] you said that one's negative...so we should factor out a....

shanice (Customer)
[00:19:30] ohhhhh

Holly F (Tutor)
[00:19:49] You got it!
[00:20:00] okay. now, to finish the factoring
[00:20:22] this factor into the the expression in parentheses times the leftovers.
[00:21:35] really we are factoring out an x-3 because both "terms" have an x-3 in common

shanice (Customer)
[00:21:59] oh ok

Holly F (Tutor)
[00:23:06] when we factor out and x-3 from -2x times x-3 we are left with what?

shanice (Customer)
[00:23:35] -2x?

Holly F (Tutor)
[00:23:43] yes, write that here
[00:24:14] when we factor out an x-3 from +1(x-3) we are left with what?
[00:24:50] there is an invisible 1 there

shanice (Customer)
[00:24:51] one of them..

Holly F (Tutor)
[00:24:58] yes, write that here

shanice (Customer)
[00:25:29] i dont understand?

Holly F (Tutor)
[00:25:54] okay. tell me exactly what you don't understand

shanice (Customer)
[00:26:14] should i write a plus one there?

Holly F (Tutor)
[00:26:33] okay, let me show you an example
[00:27:28] if i have -6x+3 i can factor out a 3, right?

shanice (Customer)
[00:28:08] mhmmm

Holly F (Tutor)
[00:28:52] when i factor a 3 out of -6x i am left with -2x. when i factor a 3 out of 3 then i am left with 1
[00:29:14] so it factors into (3)(-2x+1).
[00:29:25] do you agree?

shanice (Customer)
[00:29:33] ah, i understand

Holly F (Tutor)
[00:30:01] in our problem we are factoring out an expression (x-3) instead of a whole number like 3 from my example.

shanice (Customer)
[00:30:37] x=3 and x= 1/2

Holly F (Tutor)
[00:30:59] yes. those are the solutions

shanice (Customer)
[00:31:11] thhank you!!!