CAIE
FP1
2014
November
Q7
10 marks
Challenging +1.8
7 Let \(I _ { n } = \int _ { 0 } ^ { 1 } ( 1 - x ) ^ { n } \mathrm { e } ^ { x } \mathrm {~d} x\). Show that, for all positive integers \(n\),
$$I _ { n } = n I _ { n - 1 } - 1$$
Find the exact value of \(I _ { 4 }\).
By considering the area of the region enclosed by the \(x\)-axis, the \(y\)-axis and the curve with equation \(y = ( 1 - x ) ^ { 4 } \mathrm { e } ^ { x }\) in the interval \(0 \leqslant x \leqslant 1\), show that
$$\frac { 65 } { 24 } < \mathrm { e } < \frac { 11 } { 4 }$$
CAIE
FP1
2014
November
Q8
11 marks
Challenging +1.2
8 A circle has polar equation \(r = a\), for \(0 \leqslant \theta < 2 \pi\), and a cardioid has polar equation \(r = a ( 1 - \cos \theta )\), for \(0 \leqslant \theta < 2 \pi\), where \(a\) is a positive constant. Draw sketches of the circle and the cardioid on the same diagram.
Write down the polar coordinates of the points of intersection of the circle and the cardioid.
Show that the area of the region that is both inside the circle and inside the cardioid is
$$\left( \frac { 5 } { 4 } \pi - 2 \right) a ^ { 2 }$$
CAIE
FP1
2016
November
Q2
6 marks
Standard +0.8
2 Find the cubic equation with roots \(\alpha , \beta\) and \(\gamma\) such that
$$\begin{aligned}
\alpha + \beta + \gamma & = 3 \\
\alpha ^ { 2 } + \beta ^ { 2 } + \gamma ^ { 2 } & = 1 \\
\alpha ^ { 3 } + \beta ^ { 3 } + \gamma ^ { 3 } & = - 30
\end{aligned}$$
giving your answer in the form \(x ^ { 3 } + p x ^ { 2 } + q x + r = 0\), where \(p , q\) and \(r\) are integers to be found.
CAIE
FP1
2016
November
Q3
7 marks
Standard +0.3
3 Find a matrix \(\mathbf { A }\) whose eigenvalues are \(- 1,1,2\) and for which corresponding eigenvectors are
$$\left( \begin{array} { l }
1 \\
0 \\
0
\end{array} \right) , \quad \left( \begin{array} { l }
1 \\
1 \\
0
\end{array} \right) , \quad \left( \begin{array} { l }
0 \\
1 \\
1
\end{array} \right) ,$$
respectively.
CAIE
FP1
2016
November
Q8
11 marks
Challenging +1.2
8 A curve \(C\) has equation \(x ^ { 2 } + 4 x y - y ^ { 2 } + 20 = 0\). Show that, at stationary points on \(C , x = - 2 y\).
Find the coordinates of the stationary points on \(C\), and determine their nature by considering the value of \(\frac { \mathrm { d } ^ { 2 } y } { \mathrm {~d} x ^ { 2 } }\) at the stationary points.
CAIE
FP1
2016
November
Q9
11 marks
Challenging +1.2
9 Evaluate \(\int _ { 0 } ^ { \frac { 1 } { 2 } \pi } x \sin x \mathrm {~d} x\).
Given that \(I _ { n } = \int _ { 0 } ^ { \frac { 1 } { 2 } \pi } x ^ { n } \sin x \mathrm {~d} x\), prove that, for \(n > 1\),
$$I _ { n } = n \left( \frac { 1 } { 2 } \pi \right) ^ { n - 1 } - n ( n - 1 ) I _ { n - 2 }$$
By first using the substitution \(x = \cos ^ { - 1 } u\), find the value of
$$\int _ { 0 } ^ { 1 } \left( \cos ^ { - 1 } u \right) ^ { 3 } \mathrm {~d} u$$
giving your answer in an exact form.