Question

If a= i-j+2k and b=2i+3j-k then find (a+2b).(2a-b)..

Answer 1

Step-by-step explanation:

a= i-j+2k

2a = 2i -2j +4k

b=2i+3j-k

2b = 4i +6j -2k

(a+2b).(2a-b)

(i-j+2k + 4i +6j -2k).(2i -2j +4k - 2i-3j+k)

(5i-5j+0k).(4i -5j +5k)

20 + 25 +0

45