Edexcel CP1 2021 June — Question 4

Exam BoardEdexcel
ModuleCP1 (Core Pure 1)
Year2021
SessionJune
TopicRoots of polynomials

4 \sqrt { 3 } & - 4 \end{array} \right)$$
  1. Determine
    1. the value of \(k\),
    2. the smallest value of \(\theta\) A square \(S\) has vertices at the points with coordinates ( 0,0 ), ( \(a , - a\) ), ( \(2 a , 0\) ) and ( \(a , a\) ) where \(a\) is a constant. The square \(S\) is transformed to the square \(S ^ { \prime }\) by the transformation represented by \(\mathbf { M }\).
  2. Determine, in terms of \(a\), the area of \(S ^ { \prime }\)
    1. (a) Use the Maclaurin series expansion for \(\cos x\) to determine the series expansion of \(\cos ^ { 2 } \left( \frac { x } { 3 } \right)\) in ascending powers of \(x\), up to and including the term in \(x ^ { 4 }\)
    Give each term in simplest form.
  3. Use the answer to part (a) and calculus to find an approximation, to 5 decimal places, for $$\int _ { \frac { \pi } { 6 } } ^ { \frac { \pi } { 2 } } \left( \frac { 1 } { x } \cos ^ { 2 } \left( \frac { x } { 3 } \right) \right) \mathrm { d } x$$
  4. Use the integration function on your calculator to evaluate $$\int _ { \frac { \pi } { 6 } } ^ { \frac { \pi } { 2 } } \left( \frac { 1 } { x } \cos ^ { 2 } \left( \frac { x } { 3 } \right) \right) \mathrm { d } x$$ Give your answer to 5 decimal places.
  5. Assuming that the calculator answer in part (c) is accurate to 5 decimal places, comment on the accuracy of the approximation found in part (b).
    1. The cubic equation
    $$a x ^ { 3 } + b x ^ { 2 } - 19 x - b = 0$$ where \(a\) and \(b\) are constants, has roots \(\alpha , \beta\) and \(\gamma\)
    The cubic equation $$w ^ { 3 } - 9 w ^ { 2 } - 97 w + c = 0$$ where \(c\) is a constant, has roots \(( 4 \alpha - 1 ) , ( 4 \beta - 1 )\) and \(( 4 \gamma - 1 )\)
    Without solving either cubic equation, determine the value of \(a\), the value of \(b\) and the value of \(c\).
      1. \(\mathbf { A }\) is a 2 by 2 matrix and \(\mathbf { B }\) is a 2 by 3 matrix.
    Giving a reason for your answer, explain whether it is possible to evaluate
  6. \(\mathbf { A B }\)
  7. \(\mathbf { A } + \mathbf { B }\)
    (ii) Given that $$\left( \begin{array} { r r r } - 5 & 3 & 1
    a & 0 & 0
    b & a & b \end{array} \right) \left( \begin{array} { r r r } 0 & 5 & 0
    2 & 12 & - 1
    - 1 & - 11 & 3 \end{array} \right) = \lambda \mathbf { I }$$ where \(a\), \(b\) and \(\lambda\) are constants,
  8. determine
    • the value of \(\lambda\)
    • the value of \(a\)
    • the value of \(b\)
    • Hence deduce the inverse of the matrix \(\left( \begin{array} { r r r } - 5 & 3 & 1
      a & 0 & 0
      b & a & b \end{array} \right)\)
      (iii) Given that
    $$\mathbf { M } = \left( \begin{array} { c c c } 1 & 1 & 1
    0 & \sin \theta & \cos \theta
    0 & \cos 2 \theta & \sin 2 \theta \end{array} \right) \quad \text { where } 0 \leqslant \theta < \pi$$ determine the values of \(\theta\) for which the matrix \(\mathbf { M }\) is singular.