Question

4. Find (2 A) X(-3B).if A=21 -j and B=(j+ k)​

Answer 1

Answer:

Given,A=21-j & B=j+k

2A=2(21-j)=42-2j

-3B= -3(j+k)= -3j-3k

So,2A×(-3B)=(42-2j)×(-3j-3k)

= -126j-126k+6j^2+6jk

= -126j-126k+0+6i

= 6i-126j-126k.