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Date May 2017 Marks available 7 Reference code 17M.2.sl.TZ1.10
Level SL only Paper 2 Time zone TZ1
Command term Find Question number 10 Adapted from N/A

Question

Let f(x)=lnxf(x)=lnx and g(x)=3+ln(x2)g(x)=3+ln(x2), for x>0x>0.

The graph of gg can be obtained from the graph of ff by two transformations:

a horizontal stretch of scale factor q followed bya translation of (hk).a horizontal stretch of scale factor q followed bya translation of (hk).

Let h(x)=g(x)×cos(0.1x)h(x)=g(x)×cos(0.1x), for 0<x<40<x<4. The following diagram shows the graph of hh and the line y=xy=x.

M17/5/MATME/SP2/ENG/TZ1/10.b.c

The graph of hh intersects the graph of h1h1 at two points. These points have xx coordinates 0.111 and 3.31 correct to three significant figures.

Write down the value of qq;

[1]
a.i.

Write down the value of hh;

[1]
a.ii.

Write down the value of kk.

[1]
a.iii.

Find 3.310.111(h(x)x)dx3.310.111(h(x)x)dx.

[2]
b.i.

Hence, find the area of the region enclosed by the graphs of hh and h1h1.

[3]
b.ii.

Let dd be the vertical distance from a point on the graph of hh to the line y=xy=x. There is a point P(a, b)P(a, b) on the graph of hh where dd is a maximum.

Find the coordinates of P, where 0.111<a<3.310.111<a<3.31.

[7]
c.

Markscheme

q=2q=2     A1     N1

 

Note:     Accept q=1q=1, h=0h=0, and k=3ln(2), 2.31 as candidate may have rewritten g(x) as equal to 3+ln(x)ln(2).

 

[1 mark]

a.i.

h=0     A1     N1

 

Note:     Accept q=1, h=0, and k=3ln(2), 2.31 as candidate may have rewritten g(x) as equal to 3+ln(x)ln(2).

 

[1 mark]

a.ii.

k=3     A1     N1

 

Note:     Accept q=1, h=0, and k=3ln(2), 2.31 as candidate may have rewritten g(x) as equal to 3+ln(x)ln(2).

 

[1 mark]

a.iii.

2.72409

2.72     A2     N2

[2 marks]

b.i.

recognizing area between y=x and h equals 2.72     (M1)

egM17/5/MATME/SP2/ENG/TZ1/10.b.ii/M

recognizing graphs of h and h1 are reflections of each other in y=x     (M1)

egarea between y=x and h equals between y=x and h1

2×2.723.310.111(xh1(x))dx=2.72

5.44819

5.45     A1     N3

[??? marks]

b.ii.

valid attempt to find d     (M1)

egdifference in y-coordinates, d=h(x)x

correct expression for d     (A1)

eg(ln12x+3)(cos0.1x)x

valid approach to find when d is a maximum     (M1)

egmax on sketch of d, attempt to solve d=0

0.973679

x=0.974     A2     N4 

substituting their x value into h(x)     (M1)

2.26938

y=2.27     A1     N2

[7 marks]

c.

Examiners report

[N/A]
a.i.
[N/A]
a.ii.
[N/A]
a.iii.
[N/A]
b.i.
[N/A]
b.ii.
[N/A]
c.

Syllabus sections

Topic 6 - Calculus » 6.3 » Local maximum and minimum points.
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