Apps. and Interpretation for IBDP Maths Ebook 1 | Page 39

Exercise 9
1. A quadratic function is given by
y� � � � .
2
( x 100) 80
(a)
Find the y -intercept of the function.
The value of y is restricted such that y � 16 . In this situation, the values of x lies
between 92 and p , where p � 92 .
(b) Find the value of p .
(c)
Write down the value of x when y attains its maximum.
[2]
[2]
[1]
4
2. A quadratic function is given by
2
y x x
� � 40 � 5400 .
(a)
Write down the y -intercept of the function.
[1]
The value of y is restricted such that 5064 � y � 5400 . In this situation, the values of x
lies between p and q , where 20 � p� q.
(b) Find the values of p and q .
(c)
Write down the coordinates of the vertex.
[3]
[2]
3. The cost C of producing x books by SE Production can be modelled by
C� � � .
2
0.5( x 60) 40
(a)
Find the cost of producing 200 books.
To limit the total cost, the upper limit for the cost is set to be 240.
[2]
(b)
(c)
(d)
Find the range of the number of books.
Write down the minimum cost.
Write down the number of books produced when the cost is at its minimum.
[2]
[1]
[1]
www.seprodstore.com
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