A question on the MPE review packet: 2(x+3)^3-(x-1)(x+1)

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grybos

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Im studying for the Math Placement Exam for college and I havent ever been to great at math and I havent taken the algebras since middle school.

Ive been stuck on this problem for a little while.

2(x+3)^3-(x-1)(x+1)

Im not sure on the 2(x+3)^3 part what I would do

It says the answer to the problem is 2x^3+17x^2+54x+55 Im just not sure how to get to it

I know the the (x-1)(x+1) would be x^2+1x-1x-1, Im just confused on how to do the other side of the problem and how I get to the answer with it.

Any help would be greatly appreciated thanks.
 
Re: A question on the MPE review packet

Start with (x+3)^3 : x^3 + 9x^2 + 27x + 27
Multiply by 2: 2x^3 + 18x^2 + 54x + 54 [1]

And (x+1)(x-1) = x^2 -1 [2]

[1] - [2] = ?
 
Re: A question on the MPE review packet

I may be making myself sound stupid but how do you go about getting x^3+9x^2+27x+27 from (x+3)^3

Would you do (x+3)(x+3)(x+3)?

Or something else I'm not getting.


And I'm studying for it cause I don't to do horrible on it and end up in a remedial math class because like I said I've never been to great at math, I'm more of a History person.
 
Re: A question on the MPE review packet

I got it all mostly except for the last number I got 53 instead of 55.

Which I got

2x^3+17x^2+54x+53

But its suppose to be 55 not 53.
 
Re: A question on the MPE review packet

I got it all mostly except for the last number I got 53 instead of 55.

Which I got

2x^3+17x^2+54x+53

But its suppose to be 55 not 53.
Click to expand...

Just keep track of your signs:

54 - (-1) = 54 + 1 = 55
 
Re: A question on the MPE review packet

Ah ok I got it, thank you very much for the help.
 
Re: A question on the MPE review packet

The purpose of a "placement test" is to determine which college math class would be most appropriate for you.

If you STUDY for the placement test, and miraculously do well on it, you will most likely be placed in a class that is well above your true level of mathematics knowledge. Then what happens? I've seen it all too often....a student in such a situation is almost guaranteed to fail a class for which he/she is not prepared.

If you NEED a remedial math class to get the preparation necessary to succeed in more advanced classes, then that's where you should be....in a remedial class. That's why trying to "cram" for a placement test is generally not a good idea.
 
Re: A question on the MPE review packet

However, sharpening up some forgotten (neglected) tools is a good idea - in my opinion.
 
Ive taken all these classes before, Ive been in advanced math since 4th grade just I've never been to great at it. I finished AP statistics my Sophomore year and I haven't taken a math class since then with the exception of physics which is mostly math.
 
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