Question

If Ā=2i+3j+k and B=3i+2j+ 4k, then the value of (A + B)*(B - A) is
(1) 10(2i+j+k)
(2) 10(2i-j- k)
(3) 20(i+j-k)
(4) 10(i+2j-2k)​

Answer 1

this is a cross product.

on solving=

AxB - AxA + BxB - BxA

AxA=BxB=0

also AxB=-BxA

on simplifying.. 2(A×B)