Find the inverse of \(\begin{pmatrix} 3 & 5 \\ 1 & 2 \end{pmatrix}\)

  • A \(\begin{pmatrix} 5 & 1 \\ -3 & 2 \end{pmatrix}\)
  • B \(\begin{pmatrix} 2 & -5 \\ -1 & 3 \end{pmatrix}\)
  • C \(\begin{pmatrix} -5 & 2 \\ -1 & 3 \end{pmatrix}\)
  • D \(\begin{pmatrix} 5 & 1 \\ 2 & 3 \end{pmatrix}\)
waec 2020furthermathematics

The correct answer is B. \(\begin{pmatrix} 2 & -5 \\ -1 & 3 \end{pmatrix}\)

Let A = \(\begin{pmatrix} 3 & 5 \\ 1 & 2 \end{pmatrix}\)

|A| = (3 x 2 - 5 x 1) 

= 6 - 5

= 1

A\(^{-1}\) = \(\begin{pmatrix} 2 & -5 \\ -1 & 3 \end{pmatrix}\)

Previous question Next question