If \(\begin{pmatrix} 2 & 1 \\ 4 & 3 \end{pmatrix}\)\(\begin{pmatrix} 5 \\ 4 \end{pmatrix}\) = k\(\begin{pmatrix} 17.5 \\ 40.0 \end{pmatrix}\), find the value of k.

  • A 1.2
  • B 3.6
  • C 0.8
  • D 0.5
waec 2017furthermathematics

The correct answer is C. 0.8

\(\begin{pmatrix}  2  &  1 \\  4 & 3 \end{pmatrix}\)\(\begin{pmatrix}  5 \\ 4 \end{pmatrix}\)  = k\(\begin{pmatrix}  17.5 \\ 40.0 \end{pmatrix}\)

\(\begin{pmatrix}  10 + 4  \\  20 + 12\end{pmatrix}\) = \(\begin{pmatrix}  14 \\ 32\end{pmatrix}\) = k\(\begin{pmatrix}  17.5 \\ 40.0 \end{pmatrix}\)

k = \(\frac{14}{17.5} = \frac{32}{40} = 0.8\)

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