Apps. and Interpretation for IBDP Maths Ebook 1 | Page 38

Your Practice Set – Applications and Interpretation for IBDP Mathematics
9
Paper 1 – Inequalities Involving Quadratic Functions
Example
A quadratic function is given by
y
2
� ( x�5) � 10 .
(a)
Find the y -intercept of the function.
The value of y is restricted such that y � 19 . In this situation, the values of x lies
between p and 8, where p � 8 .
[2]
(b) Find the value of p .
(c)
Write down the value of x when y attains its minimum.
[2]
[1]
Solution
(a)
(b)
The y -intercept
2
� (0 �5) � 10
(M1) for valid approach
� 35
A1 N2
2
( x �5) �10 � 19
2
( x �5) �9 � 0
(M1) for setting inequality
By considering the graph of
y� � � ,
2
( x 5) 9
2�x
� 8.
�p
� 2
A1 N2
(c) 5 A1 N1
[2]
[2]
[1]
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