Shido88
Determine the value of f(-6), f(3/2), f(2c) and f(c+1), then simplify as much as possible
Question :
f(x) = 3x^2 - 4x
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Shido88
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@Aylin help please :D
Aylin
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Well, in the first two, just take the appropriate number and plug it in where x is. Then simplify it down.
For the third one (2c) replace x with 2c, then see what you get. Same for the fourth one.
The first two are plug'n'chug, but if you need help with the second two I'll stick around.
Shido88
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the second two, just plug it in to every x in the problem ?
Aylin
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Mhm. So f(2c) would like\[f(2c)=3 \times (2c)^{2}-4 \times (2c)\]
Shido88
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Ok let me try thanks!
Shido88
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ummm question
Aylin
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Yes?
Shido88
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kinda dumb question but for the first one f(-6)
i did
-6=3(-6)^2-4(-6)
-6=108+24
-6=132
then at this step do you add the 6 over or minus the 132 over ?? lol
Shido88
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it usually easier if one size has a (x)
Aylin
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Well, the left side is f(-6) not -6.
So when you get to f(-6)=132, you are finished with that part.
Aylin
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Since you've found the value in the range (132) that corresponds to the value of -6 in the domain.
Shido88
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i see
Shido88
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the second one i found is 3/4 hope its right
Shido88
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the third one i got: f(2c) = 4c
Shido88
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and do you divide the 2c over ?
Aylin
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I also got 3/4
Shido88
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cool :D
Aylin
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Well, with these problems you only need to simplify the right side, don't worry about the left side at all. In the third and fourth ones your answer will be in terms of c though.
Shido88
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so is my answer for the third one okay ?
Aylin
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Well, no.\[(2c)^{2}=4c^{2}\]and there is nothing in there to cancel it, so you should have a c^2 term.
Shido88
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how did you get 2c^2 on the left side ?
Shido88
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isn't it 2c ?
Aylin
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\[f(2c)=3(2c)^{2}-4(2c)\]and\[(2c)^{2}=4c^{2}\]so\[f(2c)=3 \times 4c^{2}-4(2c)\]
Shido88
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oh so you can't multiply the term -4 with 2c ?
Aylin
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You can, but I was leaving it for you to do. :P
Shido88
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ohhhh lol
Shido88
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at first i thought u can make (2c)^2 = 4c and just X 3 = 12c
Shido88
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i was wrong :|
Aylin
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Pretty close, just forgot the ^2 part of it. :P
Shido88
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u mean 12c^2 ?
Aylin
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Yep
Shido88
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but why ? :O isn't it already been done on the 2c^2 ?why ^2 another
Shido88
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@___@
Aylin
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Well\[(2c)^{2}\]is the same thing as\[2c \times 2c\]Does that make it more clear?
Shido88
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does that make 4c ?
Shido88
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and 4c x 3 = 12c lol ?
Aylin
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\[2c \times 2c = 4c^{2}\]
Shido88
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ohhh lol =___=
Shido88
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omg...my mind is somewhere else today....sorry
Aylin
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Mine is too, don't worry.
Shido88
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naw, your good :D
Shido88
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so once i got
f(2c) = 12c^2 - 8c
then what can i do next?
Aylin
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Well, at this point all of the same powers of c are together, so you're done.
Shido88
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what do you mean by "same powers of c are together" ? :d
Aylin
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Well, there's only one c^2 term and only one c term. You can't combine the c^2 and the c terms, so there is nothing left to do.
Shido88
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i see
Shido88
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the fourth one im stuck completely :D
Aylin
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Well, what is\[(c+1)^{2}\]?
Shido88
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(c+1)(c+1)
Aylin
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So FOIL it out! :P
Shido88
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ohh let see
Shido88
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c^2+2c+1 and i think u can factor it more right ?
Aylin
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Well, we don't want to factor it right now.
So now\[f(c+1)=3 \times (c^{2}+2c+1)-4 \times (c+1)\]Can you finish it from there?
Shido88
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kk hold on
Shido88
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i think it is : f(c+1)=3c^2 + 2c -1
Aylin
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Yep!
Shido88
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awesome! lol
Shido88
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so is that it ? o_0
Aylin
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Yep
Shido88
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cool!
thanks Aylin
Aylin
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You're welcome.
Shido88
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your really good in math :D
genius maybe?
Aylin
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Not really, I just want to teach math.
Shido88
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btw are you in college?
Shido88
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oh ! so your a teacher :D
Shido88
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wow! how lucky i am :D
Aylin
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Not yet. I'm a senior at RPI.
Aylin
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But next year I hope to be a teacher.
Shido88
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so your graduating next year ?
Aylin
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In May
Shido88
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oh wow, almost there!
Shido88
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how many years did you spend in RPI ?
Aylin
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The end of this year will make three years.
Shido88
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that's really quick wow
Shido88
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is this it ? "Rensselaer Polytechnic Institute" ?
Aylin
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Yeah. Not really very fast though; I spent two years at another school first.
Shido88
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I see, still not bad. I had a friend who spends 3 years at community college and transfer
Shido88
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what's the GPA for acceptance in RPI?
Aylin
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It was a community college that I came from, actually.
From another college or from high school?
Shido88
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another college
Shido88
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yeah, everybody is doing community college first now aday, cuz it's so much cheaper :D
Aylin
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Minimum is 3.0
Higher is better of course, but they also like it if you've been taking mostly science and math courses (or engineering if that's your major choice) if possible.
Shido88
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make sense.
Shido88
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well thanks so much for talking with me Aylin. I gotta get to dinner now :D
Aylin
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Like if you took a lot of math/science courses and made mostly Bs, it would look better than if you had made As taking mostly things like Art or Chorus or History
Aylin
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Bye
Shido88
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anything with science and math is better...and it's the subjects that im most terrible at. WOW..
Shido88
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well bye for now :d
Aylin
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Well, the other thing is that RPI is about $60000 a year right now, so...
Shido88
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your kidding me? no way
Shido88
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so how much for 1 semester of full time?
Shido88
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omg wow...
Aylin
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About half, but it depends on what your dining plan is, where you live, ect.
Shido88
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omg so much debts...well but it's COLLEGE that we're talking about here so no suprise.. :|
Shido88
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one time I read that article about this college couples graduated with over 200k debts
scared the hell out of me :|
Aylin
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I'm gonna have about $45K.
Shido88
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did they tell you about the rate? or how much you have to pay back once your graduated ?
I mean monthly?
Aylin
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At some point probably. I don't remember what it is right now.
Shido88
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oh i see, well i hope you can pay back all the debts without too much trouble :|
Aylin
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I should be able to.
Aylin
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Which year are you in?