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Date May 2018 Marks available 7 Reference code 18M.1.SL.TZ1.S_7
Level Standard Level Paper Paper 1 (without calculator) Time zone Time zone 1
Command term Find Question number S_7 Adapted from N/A

Question

Consider f(x), g(x) and h(x), for x∈ R where h(x) =  ( f g ) (x).

Given that g(3) = 7 , g′ (3) = 4 and f ′ (7) = −5 , find the gradient of the normal to the curve of h at x = 3.

Markscheme

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

recognizing the need to find h′      (M1)

recognizing the need to find h′ (3) (seen anywhere)      (M1)

evidence of choosing chain rule        (M1)

eg    d y d x = d y d u × d u d x , f ( g ( 3 ) ) × g ( 3 ) , f ( g ) × g

correct working       (A1)

eg   f ( 7 ) × 4 , 5 × 4

h ( 3 ) = 20       (A1)

evidence of taking their negative reciprocal for normal       (M1)

eg   1 h ( 3 ) , m 1 m 2 = 1

gradient of normal is  1 20       A1 N4

[7 marks]

Examiners report

[N/A]

Syllabus sections

Topic 5 —Calculus » SL 5.3—Differentiating polynomials, n E Z
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Topic 5 —Calculus » SL 5.6—Differentiating polynomials n E Q. Chain, product and quotient rules
Topic 5 —Calculus

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