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# The graph above shows two lines, one on the left of the y-axis and one

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Math Expert
Joined: 02 Sep 2009
Posts: 61396
The graph above shows two lines, one on the left of the y-axis and one  [#permalink]

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13 Nov 2019, 01:12
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Difficulty:

55% (hard)

Question Stats:

65% (02:40) correct 35% (02:00) wrong based on 26 sessions

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The graph above shows two lines, one on the left of the y-axis and one on the right., that represent the curve f(x) . What is the value of f(4)*f(-4) ?

(1) a = 3
(2) b = 5

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The graph above shows two lines, one on the left of the y-axis and one  [#permalink]

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13 Nov 2019, 08:32
Bunuel wrote:

The graph above shows two lines, one on the left of the y-axis and one on the right., that represent the curve f(x) . What is the value of f(4)*f(-4) ?

(1) a = 3
(2) b = 5

Are You Up For the Challenge: 700 Level Questions

Analyzing the question:
We can observe both parts of the graph are linear. We are given f(0) = a, f(-8) = c, and f(8) = b. We can express the line on the left in terms of a and c, and the line on the right in terms of a and b. However since we want to find f(-4) and f(4), which is the midpoint of the points we have, we can use an average of the two points around f(4) and f(-4),

f(4) = ( f(8) + f(0) ) / 2 = (b + a) / 2.
f(-4) = ( f(-8) + f(0) ) / 2 = (a + c) / 2.

Finally the expression we are looking for is (a + b) * (a + c) / 4. Hence we need to know a, b, and c. Since the statements only give two, it is insufficient with both.

Ans: E
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The graph above shows two lines, one on the left of the y-axis and one   [#permalink] 13 Nov 2019, 08:32
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