Question

If A = 2i+j+k and B=2i+2j+k,then |AxB| is
1)√5
2)√7
3)√11
4)√13​

Answer 1

Answer:

|A X B| = $\sqrt{5}$ units Option (1) is correct

Explanation: Note : [Change matrix sign to dterminant sign]

A X B  =  $\left[\begin{array}{ccc}i&j&k\\2&1&1\\2&2&1\end{array}\right]$  = i (1-2) -j(2-2) + k (4-2)

                                    = -i + 2k

∴ |A X B| = $\sqrt{1 + 4}$  = $\sqrt{5}$ units