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Date May 2019 Marks available 2 Reference code 19M.2.SL.TZ1.T_4
Level Standard Level Paper Paper 2 Time zone Time zone 1
Command term State Question number T_4 Adapted from N/A

Question

Consider the function  f ( x ) = x 3 5 x 2 + 6 x 3 + 1 x x > 0

The function f ( x ) = x 3 5 x 2 + 6 x 3 + 1 x x > 0 , models the path of a river, as shown on the following map, where both axes represent distance and are measured in kilometres. On the same map, the location of a highway is defined by the function g ( x ) = 0.5 ( 3 ) x + 1 .

The origin, O(0, 0) , is the location of the centre of a town called Orangeton.

A straight footpath, P , is built to connect the centre of Orangeton to the river at the point where x = 1 2 .

Bridges are located where the highway crosses the river.

A straight road is built from the centre of Orangeton, due north, to connect the town to the highway.

State the domain of P .

[2]
b.ii.

Find the distance from the centre of Orangeton to the point at which the road meets the highway.

[2]
d.

This straight road crosses the highway and then carries on due north.

State whether the straight road will ever cross the river. Justify your answer.

[2]
e.

Markscheme

0 < x 1 2    (A1)(A1)

Note: Award (A1) for both endpoints correct, (A1) for correct mathematical notation indicating an interval with two endpoints. Accept weak inequalities. Award at most (A1)(A0) for incorrect notation such as 0 − 0.5 or a written description of the domain with correct endpoints. Award at most (A1)(A0) for 0 < y 1 2 .

[2 marks]

b.ii.

g ( 0 ) = 0.5 ( 3 ) 0 + 1     (M1)

1.5 (km)   (A1)(G2)

[2 marks]

d.

domain given as x > 0 (but equation of road is x = 0 )      (R1)

OR

(equation of road is x = 0 ) the function of the river is asymptotic to x = 0        (R1)

so it does not meet the river       (A1)

Note: Award the (R1) for a correct mathematical statement about the equation of the river (and the equation of the road). Justification must be based on mathematical reasoning. Do not award (R0)(A1).

[2 marks]

e.

Examiners report

[N/A]
b.ii.
[N/A]
d.
[N/A]
e.

Syllabus sections

Topic 2—Functions » SL 2.2—Functions, notation domain, range and inverse as reflection
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Topic 2—Functions » SL 2.4—Key features of graphs, intersections using technology
Topic 2—Functions » SL 2.5—Modelling functions
Topic 2—Functions

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