Edexcel CP AS 2020 June — Question 6

Exam BoardEdexcel
ModuleCP AS (Core Pure AS)
Year2020
SessionJune
TopicLinear transformations

$$\mathbf { A } = \left( \begin{array} { c c } 2 & a
a - 4 & b \end{array} \right)$$ where \(a\) and \(b\) are non-zero constants.
Given that the matrix \(\mathbf { A }\) is self-inverse,
  1. determine the value of \(b\) and the possible values for \(a\). The matrix \(\mathbf { A }\) represents a linear transformation \(M\).
    Using the smaller value of \(a\) from part (a),
  2. show that the invariant points of the linear transformation \(M\) form a line, stating the equation of this line.
    (ii) $$\mathbf { P } = \left( \begin{array} { c c } p & 2 p
    - 1 & 3 p \end{array} \right)$$ where \(p\) is a positive constant.
    The matrix \(\mathbf { P }\) represents a linear transformation \(U\).
    The triangle \(T\) has vertices at the points with coordinates ( 1,2 ), ( 3,2 ) and ( 2,5 ). The area of the image of \(T\) under the linear transformation \(U\) is 15
  3. Determine the value of \(p\). The transformation \(V\) consists of a stretch scale factor 3 parallel to the \(x\)-axis with the \(y\)-axis invariant followed by a stretch scale factor - 2 parallel to the \(y\)-axis with the \(x\)-axis invariant. The transformation \(V\) is represented by the matrix \(\mathbf { Q }\).
  4. Write down the matrix \(\mathbf { Q }\). Given that \(U\) followed by \(V\) is the transformation \(W\), which is represented by the matrix \(\mathbf { R }\), (c) find the matrix \(\mathbf { R }\).