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Date November 2015 Marks available 5 Reference code 15N.1.sl.TZ0.8
Level SL only Paper 1 Time zone TZ0
Command term Find Question number 8 Adapted from N/A

Question

The following diagram shows part of the graph of a quadratic function f.

The vertex is at (1, 9), and the graph crosses the y-axis at the point (0, c).

The function can be written in the form f(x)=(xh)2+k.

Write down the value of h and of k.

[2]
a.

Find the value of c.

 

[2]
b.

Let g(x)=(x3)2+1. The graph of g is obtained by a reflection of the graph of f in the x-axis, followed by a translation of (pq).


Find the value of p and of q.

[5]
c.

Find the x-coordinates of the points of intersection of the graphs of f and g.

[7]
d.

Markscheme

h=1, k=9(accept (x1)29)     A1A1     N2

[2 marks]

a.

METHOD 1

attempt to substitute x=0 into their quadratic function     (M1)

egf(0), (01)29

c=8     A1     N2

METHOD 2

attempt to expand their quadratic function     (M1)

egx22x+19, x22x8

c=8     A1     N2

[2 marks]

b.

evidence of correct reflection     A1

eg((x1)29), vertex at (1, 9), y-intercept at (0, 8)

valid attempt to find horizontal shift     (M1)

eg1+p=3, 13

p=2     A1     N2

valid attempt to find vertical shift     (M1)

eg9+q=1, 91, 9+q=1

q=8     A1     N2

 

Notes:     An error in finding the reflection may still allow the correct values of p and q to be found, as the error may not affect subsequent working. In this case, award A0 for the reflection, M1A1 for p=2, and M1A1 for q=8.

If no working shown, award N0 for q=10.

[5 marks]

c.

valid approach (check FT from (a))     M1

egf(x)=g(x), (x1)29=(x3)2+1

correct expansion of both binomials     (A1)

egx22x+1, x26x+9

correct working     (A1)

egx22x8=x2+6x8

correct equation     (A1)

eg2x28x=0, 2x2=8x

correct working     (A1)

eg2x(x4)=0

x=0, x=4     A1A1     N3

[7 marks]

Total [16 marks]

d.

Examiners report

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

Syllabus sections

Topic 2 - Functions and equations » 2.3 » Transformations of graphs.
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