epdf.pub_cbest-cliffs-test-prep13a9b242c7cb4125e6cca92d00a73d5a41681

Part II: Analysis of Exam Areas
Now try 2:
2 x=
y
22=y ^ h
4=y
Try it again. No matter what positive integer you plug in for x, y is always positive
and even. Therefore, the answer is A.
21. If x>
1, which of the following decreases as x decreases?
I. x + x 2
II. 2x 2 - x
III.
1
x+
1
A. I only
B. II only
C. III only
D. I and II only
E. II and III only
You can solve this problem most easily by taking each situation and substituting
simple numbers.
However, in the first situation — I. x+ x 2
— you should recognize that this expression
will decrease as x decreases.
Trying x= 2produces 2+ ^2h 2
, which equals 6.
2
Now trying x= 3gives you 3+ ^h 3 = 12.
Notice that choices B, C, and E are already eliminated because they do not contain
I. You should also realize that now you need to try only the values in II —
because III is not paired with I as an answer choice, III cannot be one of the
answers.
2
2
Trying x = 2 in the expression 2^xh
- xgives you 22 ^ h - 2, or 2^4h
- 2, which
leaves 6.
Now trying x= 3gives you 2^h 3 2 - 3, or 2^9h
- 3= 18- 3=
15. This expression
also decreases as x decreases. Therefore, the correct answer is choice D. Notice
that III was not even attempted because it was not one of the possible choices.
Be sure to make logical substitutions. Use the appropriate type of number — a
positive number, a negative number, zero, and so on — to get the full picture.
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