Edexcel
FP1
2013
January
Q8
8. (a) Prove by induction that, for \(n \in \mathbb { Z } ^ { + }\),
$$\sum _ { r = 1 } ^ { n } r ( r + 3 ) = \frac { 1 } { 3 } n ( n + 1 ) ( n + 5 )$$
(b) A sequence of positive integers is defined by
$$\begin{aligned}
u _ { 1 } & = 1
u _ { n + 1 } & = u _ { n } + n ( 3 n + 1 ) , \quad n \in \mathbb { Z } ^ { + }
\end{aligned}$$
Prove by induction that
$$u _ { n } = n ^ { 2 } ( n - 1 ) + 1 , \quad n \in \mathbb { Z } ^ { + }$$
Edexcel
FP1
2014
January
Q3
3. A rectangular hyperbola has parametric equations
$$x = 2 t , \quad y = \frac { 2 } { t } , \quad t \neq 0$$
Points \(P\) and \(Q\) on this hyperbola have parameters \(t = \frac { 1 } { 2 }\) and \(t = 4\) respectively.
The line \(L\), which passes through the origin \(O\), is perpendicular to the chord \(P Q\).
Find an equation for \(L\).
Edexcel
FP1
2014
January
Q4
4.
$$f ( x ) = 2 x ^ { \frac { 1 } { 2 } } - \frac { 6 } { x ^ { 2 } } - 3 , \quad x > 0$$
A root \(\beta\) of the equation \(\mathrm { f } ( x ) = 0\) lies in the interval \([ 3,4 ]\).
Taking 3.5 as a first approximation to \(\beta\), apply the Newton-Raphson process once to \(\mathrm { f } ( x )\) to obtain a second approximation to \(\beta\). Give your answer to 3 decimal places.
Edexcel
FP1
2014
January
Q6
6. (a) Use the standard results for \(\sum _ { r = 1 } ^ { n } r ^ { 3 }\) and \(\sum _ { r = 1 } ^ { n } r\) to show that for all positive integers \(n\),
$$\sum _ { r = 1 } ^ { n } r ( r + 1 ) ( r - 1 ) = \frac { 1 } { 4 } n ( n + 1 ) ( n - 1 ) ( n + a )$$
where \(a\) is an integer to be determined.
(b) Hence find the value of \(n\), where \(n > 1\), that satisfies
$$\sum _ { r = 1 } ^ { n } r ( r + 1 ) ( r - 1 ) = 10 \sum _ { r = 1 } ^ { n } r ^ { 2 }$$
Edexcel
FP1
2014
January
Q10
10. (i) A sequence of numbers \(u _ { 1 } , u _ { 2 } , u _ { 3 } , \ldots\), is defined by
$$u _ { n + 1 } = 5 u _ { n } + 3 , \quad u _ { 1 } = 3$$
Prove by induction that, for \(n \in \mathbb { Z } ^ { + }\),
$$u _ { n } = \frac { 3 } { 4 } \left( 5 ^ { n } - 1 \right)$$
(ii) Prove by induction that, for \(n \in \mathbb { Z } ^ { + }\),
$$f ( n ) = 5 \left( 5 ^ { n } \right) - 4 n - 5 \text { is divisible by } 16 .$$
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