Another way to answer the question is to remember that
the distance between two
numbers on the number line is equal to the absolute value of the difference of the two
numbers. For example, the distance between
and 1 is
and the distance
between 10 and 1 is
The correct answer is Choice A
,
3.
Figure 5
The figure above shows the graph
of the function
f
, defined by
for all numbers
x
. For
which of the following functions
g,
defined for all numbers
x,
does the graph of
g
intersect the
graph of
f
?
A.
B.
C.
D.
E.
Explanation
You can see that all five choices are linear functions whose graphs are lines with various slopes
and
y
-intercepts. The graph of Choice A is a line with slope 1 and
y
-intercept
shown in
Figure 6.
23
Figure 6
It is clear that this line will not
intersect the graph of
f
to the left of the
y
-axis. To the right of
the
y
-axis, the graph of
f
is a line with slope 2, which is greater than slope 1. Consequently,
as the value of
x
increases, the value of
y
increases
faster for
f
than for
g
, and therefore the
graphs do not intersect to the right of the
y
-axis. Choice B is similarly ruled out. Note that if
the
y
-intercept of either of the lines in Choices A and B were greater than or equal to 4
instead of less than 4, they would
intersect the graph of
f
.
Choices C and D are lines with slope 2 and
y
-intercepts less than 4. Hence, they are parallel
to the graph of
f
(to the right of the
y
-axis) and therefore will not intersect it. Any line with a
slope greater than 2 and a
y
-intercept less than 4, like the line in Choice E, will
intersect the
graph of
f
(to the right of the
y
-axis).
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