WJEC Further Unit 4 Specimen — Question 6

Exam BoardWJEC
ModuleFurther Unit 4 (Further Unit 4)
SessionSpecimen
Topic3x3 Matrices

6. The matrix \(\mathbf { M }\) is given by $$\mathbf { M } = \left[ \begin{array} { l l l } 2 & 1 & 3
1 & 3 & 2
3 & 2 & 5 \end{array} \right]$$
  1. Find
    1. the adjugate matrix of \(\mathbf { M }\),
    2. hence determine the inverse matrix \(\mathbf { M } ^ { - 1 }\).
  2. Use your result to solve the simultaneous equations $$\begin{aligned} & 2 x + y + 3 z = 13
    & x + 3 y + 2 z = 13
    & 3 x + 2 y + 5 z = 22 \end{aligned}$$