8.2.1 Graphs of Functions, PT3 Focus Practice
Question 1:
In the figure shown, when x = 4, the value of y is
Solution:
T is the point on the graph where x = 4.
Hence, when x = 4, y = 5.
Question 2:
Diagram shows the graph of a function on a Cartesian plane.
The equation that represents the function is
Solution:
Use points (0, 6) and (-3, 0) to determine the function.
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Function
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Value of y when
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x = 0
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x = –3
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y = x + 3
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3
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0
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y = x – 3
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–3
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–6
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y = 2x + 6
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6
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0 (correct)
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y = 2x – 6
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–6
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–12
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Question 3:
Table below shows the values of variables x and y of a function.
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x
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–2
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0
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1
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y
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–6
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2
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3
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Which of the following functions is satisfied by the ordered pair?
A y = 7x + 2
B y = x3 + 2
C y = x + x2 – 2
D y = x2 + 2
Solution:
Only y = x3 + 2 is satisfied by all the ordered pairs.
(i) –6 = (–2)3 + 2
(ii) 2 = 03 + 2
(iii) 3 = 13 + 2
Answer = B