Analysis and Approaches for IBDP Maths Ebook 1 | Page 17

Front Page
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Example
Paper 1 Section A – Find the coordinates
of the vertex in
2
Let f ( x) � ( x � 2)( x � 4) .
(a) Write down the x -intercepts of the graph of f .
(b) Find the coordinates of the vertex of the graph of f .
[2]
[4]
Solution
(a) x � 2 and x �� 4
A2 N2
(b)
2 �( �4)
h �
2
(M1) for correct formula
h �� 1
A1
k � ( �1� 2)( �1� 4)
(M1) for finding k
k �� 9
Thus, the coordinates of the vertex are ( �1, � 9) . A1 N3
[2]
[4]
Exercise 3
1. Let f ( x) � ( x �7)( x � 5) .
(a) Write down the x -intercepts of the graph of f .
(b) Find the coordinates of the vertex of the graph of f .
[2]
[4]
2. Let f ( x) � 2( x �1)( x � 6) .
(a) Write down the x -intercepts of the graph of f .
(b) Find the coordinates of the vertex of the graph of f .
[2]
[4]
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