Question

Find (2A)xx(-3B), if A =2hati - hatj and B =(hatj+hatk)

Answer 1

Given:

A =2hati - hatj and

B =hatj +hatk

To Find:

(2A)xx(-3B) = -6 ( AxB )

Solution:

Given,

• A = 2i - j

• B = j + k

We know cross product is given by,

• AxB = $\left[\begin{array}{ccc}i&j&k\\2&-1&0\\0&1&1\end{array}\right]$

Therefore,

• AxB = i ( -1 - 0 ) - j ( 2 - 0 ) + k ( 2 - 0 )
• AxB = -i -2j + 2k

Therefore

• (2A)xx(-3B) = -6 ( AxB ) = 6i + 12j - 12k

Answer 2

Answer:

First attempt DC Pandey