Question

$\ddot{A} = \left| \begin{matrix} 18 & 40 & 89 \\ 40 & 89 & 198 \\ 89 & 198 & 440 \end{matrix} \right|$ is equal to

• A. 1
• B. -1
• C. Zero
• D. ∆ = 2

Answer 1

Answer: (B)

-1

Answer 2

18 & 40 & 89 \\ 4 & 9 & 20 \\ - 1 & - 2 & - 5 \end{matrix} \right|$$ (operating R₂→R₂ – 2R₁ & R₃→ R₃ – 5R₁) = $\left| \begin{matrix} 18 & 40 & 89 \\ 0 & 1 & 0 \\ - 1 & - 2 & - 5 \end{matrix} \right|$ (by R₂ → R₂ + 4R₃) = [1 (-90 + 89)] = -1.