Question

given that r1=3i-2j+k, r2=2i-4j-3k, r3=-i+2j+2k, find the magnitude of
a) R=r1+r2+r3
b) A= 2r1-3r2-5r3

Answer 1

a)

$$\vec{R}=(3,-2,1)+(2,-4,-3)+(-1,2,2)\\\vec{R}=(4,-4,0)$$

b)

$$\vec{A}=2(3,-2,1)-3(2,-4,-3)-5(-1,2,2)\\\vec{A}=(5,-2,1)$$