Question 7, Exercise 2.2

Solutions of Question 7 of Exercise 2.2 of Unit 02: Matrices and Determinants. This is unit of A Textbook of Mathematics for Grade XI is published by Khyber Pakhtunkhwa Textbook Board (KPTB or KPTBB) Peshawar, Pakistan.

Evaluate $\left| \begin{matrix}3860 & 3861 \\3862 & 3863 \end{matrix} \right|$

Given $$\left| \begin{matrix} 3860 & 3861 \\ 3862 & 3863 \\ \end{matrix} \right|=14911180-14911182$$ $$=-2$$

Evaluate $\left| \begin{matrix}81 & 82 & 83 \\84 & 85 & 86 \\87 & 88 & 89\end{matrix} \right|$

Given $$\left| \begin{matrix} 81 & 82 & 83 \\ 84 & 85 & 86 \\ 87 & 88 & 89 \\ \end{matrix} \right|=81(7565-7568)-82(7476-7482)+83(7392-7395)$$ $$=-243+492-249$$ $$=0$$

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