Evaluate 2&5 -1&-1 1. 3 2. -7 3. 5 4. -2 - Vidyadip

Question

Evaluate $\begin{bmatrix}2&5\\-1&-1\end{bmatrix}$

3
-7
5
-2

✓

Answer

3

Solution:
Expanding along $\text{R}_1,$ we get
$\triangle=2(-1)-5(-1)=2+5$
$=3$

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