OCR MEI FP2 2012 June — Question 3

Exam BoardOCR MEI
ModuleFP2 (Further Pure Mathematics 2)
Year2012
SessionJune
Topic3x3 Matrices

3
  1. Find the value of \(a\) for which the matrix $$\mathbf { M } = \left( \begin{array} { r r r } 1 & 2 & 3
    - 1 & a & 4
    3 & - 2 & 2 \end{array} \right)$$ does not have an inverse.
    Assuming that \(a\) does not have this value, find the inverse of \(\mathbf { M }\) in terms of \(a\).
  2. Hence solve the following system of equations. $$\begin{aligned} x + 2 y + 3 z & = 1
    - x + 4 z & = - 2
    3 x - 2 y + 2 z & = 1 \end{aligned}$$
  3. Find the value of \(b\) for which the following system of equations has a solution. $$\begin{aligned} x + 2 y + 3 z & = 1
    - x + 6 y + 4 z & = - 2
    3 x - 2 y + 2 z & = b \end{aligned}$$ Find the general solution in this case and describe the solution geometrically.