Minuses problem?

Question

Sample GMAT question wants me to calculate:
(x+2) - (x+1) - (x-1) - (x-2) where x = -100.

In my reckoning this would be:
(-98) - (-99) - (-101) - (-102) = 204

However the test software tells me it is:
-98 - 99 - (-101) - (-102) = 6

I have copied out the original formula and triple checked it; but I do not understand why it treats -99 differently to -101.

Thanks in advance.

Answer 1

I think the test book is incorrect. Either they wrote the problem wrong or forgot to distribute all the negatives. My advice, be careful with test prep books....they have a lot of mistakes.

McGraw Hill and Kaplan usually have the most errors (in my experience) and Barron's has very little mistakes but Barrons is much harder than what you'll actually be testing for. I personally like that though, because it definitley prepares you.

Hope it helps.

Answer 2

(x + 2) - (x + 1) - (x - 1) - (x - 2) =
x + 2 - x - 1 - x + 1 - x + 2 =
-2x + 4 =
-2(-100) + 4 =
200 + 4 = 204

NB Have you or test software manipulated the minuses correctly?
I agree with you the answer is 204!!!!

Answer 3

(x+2) - (x+1) - (x-1) - (x-2) where x = -100

(-100 + 2) - (-100 + 1) - (-100 - 1) - (-100 - 2)

(-98) - (-99) - (-101) - (-102)

-98 + 99 + 101 + 102

204

Answer 4

Let's do it a bit differently:
Let's simplify the original expression:
(x+2) - (x+1) = 1
1 - (x-1) = 2-x
2-x -(x-2) = -2x + 4.
Now plug in x = -100 to get 204.
Your answer is correct.

Answer 5

The answer is 204. You did it correctly. Move on to the next questions and good luck!

Answer 6

nope. youre right . just carry on. softwares mistake.
its a good idea to ask the makers, they may have done it for a reason.