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Date November 2018 Marks available 7 Reference code 18N.2.AHL.TZ0.H_2
Level Additional Higher Level Paper Paper 2 Time zone Time zone 0
Command term Find Question number H_2 Adapted from N/A

Question

A function  f satisfies the conditions  f ( 0 ) = 4 f ( 1 ) = 0 and its second derivative is f ( x ) = 15 x + 1 ( x + 1 ) 2 , x ≥ 0.

Find f ( x ) .

Markscheme

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

f ( x ) = ( 15 x + 1 ( x + 1 ) 2 ) d x = 10 x 3 2 1 x + 1 ( + c )       (M1)A1A1

Note: A1 for first term, A1 for second term. Withhold one A1 if extra terms are seen.

 

f ( x ) = ( 10 x 3 2 1 x + 1 + c ) d x = 4 x 5 2 ln ( x + 1 ) + c x + d      A1

Note: Allow FT from incorrect  f ( x )  if it is of the form  f ( x ) = A x 3 2 + B x + 1 + c .

Accept  ln | x + 1 | .

 

attempt to use at least one boundary condition in their  f ( x )       (M1)

x = 0 y = 4

⇒  d = 4       A1

x = 1 y = 0

⇒  0 = 4 ln 2 + c 4

⇒   c = ln 2 ( = 0.693 )       A1

f ( x ) = 4 x 5 2 ln ( x + 1 ) + x ln 2 4

 

[7 marks]

Examiners report

[N/A]

Syllabus sections

Topic 5 —Calculus » SL 5.10—Indefinite integration, reverse chain, by substitution
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Topic 5 —Calculus

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