GMAT Prep2?? (-x)

Please Help..

Thanks.

The mistake you made is in your answer choice.

When you plug in -1 for x, you end up with 1 as the answer.

sqroot -(-1)|-1| = sqroot 1 = 1

When you are looking at the answer choices you plug the -1 back into the answer choices:

eliminate B and C.

A = -(-1) = 1
D = -1
E = 1i, which is an imaginary number. Answer is A.

For the second one, the best way is to redraw the picture and plug in the numbers for r and s. I plugged in 5 for r and 2 for s. Then, just solve this problem, and plug the numbers into the answer choices to get the answer. This all took me 2 minutes and 23 seconds.

1) Get the area of the entire circle: 5^2pi = 25pi

2) Get the area of the circle without the shaded region around it:
5 - 2 = 3 ----> 3^2pi = 9pi

3) Get the area of the shaded region: 25pi - 9pi = 16pi

A = 9pi eliminate

B = 21pi eliminate

C = 6pi eliminate

D = 40pi eliminate

E = 16pi choose E.

Just a friendly request.. can you please post each question in a separate thread... helps everyone to keep focused..

Thanks in advance

The area of the metal frame is pie(r+s)^2 - pie(r)^2

which will be pie(r^2+2rs+s^2) - pie(r)^2

= pie s (2r+s)

What am I missing here?

Im sorry..The area of the metal frame would be


pie(r)^2 - pie(r-s)^2

pie(r)^2-pie(r^2-2sr+s^2)

pie(r)^2-pie(r)^2+pie(2sr)-pie(s)^2

pie(2sr)-pie(s)^2

pie(s) [2r-s]

This should not take more than a minute

There is nothing wrong with the approach that moneyman used. Algebra should be applied with some problems. However, keep in mind: during the exam, you are more likely to make a mistake with applied algebra than you are doing arithmetic.

One question per thread please.