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Date November 2017 Marks available 2 Reference code 17N.1.SL.TZ0.T_11
Level Standard Level Paper Paper 1 (with calculator from previous syllabus) Time zone Time zone 0
Command term Find Question number T_11 Adapted from N/A

Question

A quadratic function f is given by f ( x ) = a x 2 + b x + c . The points ( 0 ,   5 ) and ( 4 ,   5 ) lie on the graph of y = f ( x ) .

The y -coordinate of the minimum of the graph is 3.

Find the equation of the axis of symmetry of the graph of y = f ( x ) .

[2]
a.

Write down the value of c .

[1]
b.

Find the value of a and of b .

[3]
c.

Markscheme

* This question is from an exam for a previous syllabus, and may contain minor differences in marking or structure.

x = 2     (A1)(A1)     (C2)

 

Note:     Award (A1) for x = (a constant) and (A1) for 2 .

 

[2 marks]

a.

( c = )   5     (A1)     (C1)

[1 mark]

b.

b 2 a = 2

a ( 2 ) 2 2 b + 5 = 3 or equivalent

a ( 4 ) 2 4 b + 5 = 5 or equivalent

2 a ( 2 ) + b = 0 or equivalent     (M1)

 

Note:     Award (M1) for two of the above equations.

 

a = 0.5     (A1)(ft)

b = 2     (A1)(ft)     (C3)

 

Note:     Award at most (M1)(A1)(ft)(A0) if the answers are reversed.

Follow through from parts (a) and (b).

 

[3 marks]

c.

Examiners report

[N/A]
a.
[N/A]
b.
[N/A]
c.

Syllabus sections

Topic 5 —Calculus » SL 5.8—Testing for max and min, optimisation. Points of inflexion
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