Question

If a = 2i + j - k, b = -i + 2j - 4k and c = i + j + k, then find (a × b).(b × c).

Answer 1

Answer:

Step-by-step explanation:

a x b= (-4+2)i+(-4-1)j+(4+1)k

       = -2i-5j+5k

b x c= (2+4)i+(4-1)j+(-1-2)k

       = 6i+3j-3k

(a x b).(b x c)= (-2*6)+(-5*3)+(5*-3)

                    = -42