SPS
SPS FM Pure
2024
September
Q5
5. (a) Show that the binomial expansion of
$$( 4 + 5 x ) ^ { \frac { 1 } { 2 } }$$
in ascending powers of \(x\), up to and including the term in \(x ^ { 2 }\) is
$$2 + \frac { 5 } { 4 } x + k x ^ { 2 }$$
giving the value of the constant \(k\) as a simplified fraction.
(b) (i) Use the expansion from part (a), with \(x = \frac { 1 } { 10 }\), to find an approximate value for \(\sqrt { 2 }\) Give your answer in the form \(\frac { p } { q }\) where \(p\) and \(q\) are integers.
(ii) Explain why substituting \(x = \frac { 1 } { 10 }\) into this binomial expansion leads to a valid approximation.
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SPS
SPS FM Pure
2024
September
Q8
8. (a) Express \(2 \sin \theta - 1.5 \cos \theta\) in the form \(R \sin ( \theta - \alpha )\), where \(R > 0\) and \(0 < \alpha < \frac { \pi } { 2 }\) State the value of \(R\) and give the value of \(\alpha\) to 4 decimal places.
Tom models the depth of water, \(D\) metres, at Southview harbour on 18th October 2017 by the formula
$$D = 6 + 2 \sin \left( \frac { 4 \pi t } { 25 } \right) - 1.5 \cos \left( \frac { 4 \pi t } { 25 } \right) , \quad 0 \leqslant t \leqslant 24$$
where \(t\) is the time, in hours, after 00:00 hours on 18th October 2017.
Use Tom's model to
(b) find the depth of water at 00:00 hours on 18th October 2017,
(c) find the maximum depth of water,
(d) find the time, in the afternoon, when the maximum depth of water occurs. Give your answer to the nearest minute.
Tom's model is supported by measurements of \(D\) taken at regular intervals on 18th October 2017. Jolene attempts to use a similar model in order to model the depth of water at Southview harbour on 19th October 2017.
Jolene models the depth of water, \(H\) metres, at Southview harbour on 19th October 2017 by the formula
$$H = 6 + 2 \sin \left( \frac { 4 \pi x } { 25 } \right) - 1.5 \cos \left( \frac { 4 \pi x } { 25 } \right) , \quad 0 \leqslant x \leqslant 24$$
where \(x\) is the time, in hours, after 00:00 hours on 19th October 2017.
By considering the depth of water at 00:00 hours on 19th October 2017 for both models,
(e) (i) explain why Jolene's model is not correct,
(ii) hence find a suitable model for \(H\) in terms of \(x\).
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SPS
SPS FM Pure
2025
February
Q3
3
\end{array} \right) , \quad \mathbf { B } = \left( \begin{array} { r r r }
2 & 0 & 3
1 & - 1 & 3
\end{array} \right) , \quad \mathbf { C } = \left( \begin{array} { l l }
1 & 3
\end{array} \right)$$
Calculate all possible products formed from two of these three matrices.
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2. The complex number \(z\) satisfies the equation \(z ^ { 2 } - 4 \mathrm { i } z ^ { * } + 11 = 0\).
Given that \(\operatorname { Re } ( z ) > 0\), find \(z\) in the form \(a + b \mathrm { i }\), where \(a\) and \(b\) are real numbers.
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3.
Prove by mathematical induction that \(\sum _ { r = 1 } ^ { n } ( r \times r ! ) = ( n + 1 ) ! - 1\) for all positive integers \(n\).
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SPS
SPS FM Pure
2025
February
Q4
4. The cubic equation
$$2 x ^ { 3 } + 6 x ^ { 2 } - 3 x + 12 = 0$$
has roots \(\alpha , \beta\) and \(\gamma\).
Without solving the equation, find the cubic equation whose roots are ( \(\alpha + 3\) ), ( \(\beta + 3\) ) and \(( \gamma + 3 )\), giving your answer in the form \(p w ^ { 3 } + q w ^ { 2 } + r w + s = 0\), where \(p , q , r\) and \(s\) are integers to be found.
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