Question

if A= 2 i + J and B = J - K the magnitude of 2 A + 3 b is

Answer 1

2A+3B
2(2i+j)+3(j-k)
4i+2j+3j-3k
4i+5j-3k
magnitude=√16+25+9
= √50
=5√2

Answer 2

as A=2i+j,B=j-k
so 2a+3b=4I+5j-3k
so magnitude is root of (4^2+5^2+3^2)=root16+25+9
= root 50=50^1/2