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–24 – (x2 – 2 =

–24 – (x2 – 1)2 =
(A)    x4 + 2x2 + 15
(B) ...
(C) ...
(D) ...
(E) ...

*This question is included in Nova Math - Diagnostic/Review:

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Posted: 02/24/2012 14:32
why wouldn't 16 be negative if -2 • -2 = 4, 4 • -2 = -8, -8 • -2 = 16 . why is it negative AFTER the math is done.

also, where did the 2x come from? why was it turned into a quadratic?
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Posted: 02/24/2012 18:01
Markedia, here is the walk through to answer your 2nd question.
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Posted: 02/24/2012 18:06
It is a good idea for you to review the foil method: http://en.wikipedia.org/wiki/FOIL_method
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Posted: 02/24/2012 18:22
Markedia, thanks for using the app.

Why is 16 negative? Remember the order of operations: PEMDAS (Parentheses, Exponents, Multiplication, Division, Addition, Subtraction). In the case of -2^4, power or exponent has precedence over multiplication (the negative sign is the same as multiplying by -1). Written a different way, it is the same as -1 x 2^4 = -16.
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Posted: 04/10/2012 16:10
I have the book "cracking the GRE 2012" and the chapter on exponents p.188 says "a negative number raised to an even power becomes positive, for example (-2)^2 =4 because -2 X -2 = 4.
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Posted: 04/10/2012 16:14
It seems this contradicts how you suggest to multiply by -1.
Ex. -2^2 = 4 but if you follow what you suggest -1 X 2^2 is incorrect
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Posted: 04/10/2012 16:19
Any thoughts?
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Posted: 07/18/2012 23:48
Will,

Please read the posts at 02/24 from Joel. The key is operation order.

(-2)^2 is not the same as -2^2. Here is why:

With Parentheses, (-2)^2= (-2)x(-2)=4;
Without Parentheses, -2^2 = -(2^2)=-(2x2) = -4.
because PEMDAS tells us that E should be operated before S, so "2^2" will happen before negative "-".

I hope I answered your question.
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Posted: 04/10/2012 17:23
I get it. That's tricky!! Thanks
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Posted: 04/10/2012 16:19
Any thoughts?
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Posted: 06/14/2012 18:10
So does it mean power 4 affects on 2 and not -2?
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Posted: 03/01/2013 04:29
So, without this →( ),

-2^4 would not become 16.

(-2)^4 will be 16, right?
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Posted: 03/01/2013 05:52
Hi Yoshinori,

Yes, that is correct.

-2^4 = -16

and

(-2)^4 = 16

Just remember that the negative sign must be in encased in parentheses for the expression to be positive.

Nova Press
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–24 – (x2 – 2 = 
Posted: 03/16/2017 10:32
But in few of your questions -2 (without brackets means the negative sign accompanied with 2.
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