Sat 2015 Practice Test #1 Answer Explanations

Choice B is correct.
The minimum value of the function corresponds 
to the 
y
-coordinate of the point on the graph that has the smallest 
y
-coordinate on the graph. Since the smallest 
y
-coordinate belongs to
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Iơ ơ7KHUHIRUHWKHPLQLPXPYDOXHRII
(
[
) is at 
[ ơ
&KRLFH$LVLQFRUUHFWơLVWKHOHDVWYDOXHIRUDQ[
-coordinate, not the 
y
-coordinate, of a point on the graph of 
y
= 
I
(
[
). Choice C is incorrect;
it is the minimum value of 
I
, not the value of 
[
that corresponds to the
minimum of 
I
. Choice D is incorrect; it is the value of 
[
for which the
value of 
I
(
[
) has its maximum, not minimum.
QUESTION 18 
Choice A is correct.
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LQHTXDOLWLHVVXEVWLWXWLQJIRU[DQGIRU
y
in the given system must 
result in two true inequalities. After this substitution, 
y
ơ[
+ 
D
EHFRPHVD
, and 
y
> 
[
+ 
EEHFRPHV!E
. Hence, 
D
is positive and 
E
is negative. Therefore, 
D
> 
E
. 
Choice B is incorrect because 
E
> 
D
cannot be true if 
E
is negative 
and 
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DQH[DPSOHZKHUHLVDVROXWLRQWRWKHV\VWHPEXW_D__E
|; 
for example, if 
D
= 6 and 
E ơ&KRLFH'LVLQFRUUHFWEHFDXVHWKH
equation 
D ơEGRHVQŞWKDYHWREHWUXHIRUH[DPSOHLVDVROXWLRQ
to the system of inequalities if 
D
= 1 and 
E ơ
QUESTION 19