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Date May Specimen Marks available 2 Reference code SPM.1.sl.TZ0.14
Level SL only Paper 1 Time zone TZ0
Command term Write down Question number 14 Adapted from N/A

Question

A sketch of the function \(f(x) = 5{x^3} - 3{x^5} + 1\) is shown for \( - 1.5 \leqslant x \leqslant 1.5\) and \( - 6 \leqslant y \leqslant 6\) .

Write down \(f'(x)\) .

[2]
a.

Find the equation of the tangent to the graph of \(y = f(x)\) at \((1{\text{, }}3)\) .

[2]
b.

Write down the coordinates of the second point where this tangent intersects the graph of \(y = f(x)\) .

[2]
c.

Markscheme

\(f'(x) = 15{x^2} - 15{x^4}\)     (A1)(A1)     (C2)

 

Note: Award a maximum of (A1)(A0) if extra terms seen.

a.

\(f'(1) = 0\)     (M1)

 

Note: Award (M1) for \(f'(x) = 0\) .

 

\(y = 3\)     (A1)(ft)     (C2)

 

Note: Follow through from their answer to part (a).

b.

\(( - 1.38{\text{, }}3)\) \(( - 1.38481 \ldots {\text{, }}3)\)     (A1)(ft)(A1)(ft)     (C2)

 

Note: Follow through from their answer to parts (a) and (b).

Note: Accept \(x = - 1.38\), \(y = 3\) (\(x = - 1.38481 \ldots\) , \(y = 3\)) .

c.

Examiners report

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

Syllabus sections

Topic 7 - Introduction to differential calculus » 7.2 » The derivative of functions of the form \(f\left( x \right) = a{x^n} + b{x^{n - 1}} + \ldots \), where all exponents are integers.
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