Question

The vectors A= (1 m)î - (2 m)j and B = (2 m)î – (4 m)ſ. Calculate the value of A.B.
(A) 10 m
(B) -20 m
(C) 5 m
(D) –10 m​

Answer 1

Answer:

(A) 10m

Explanation:

A = (1 m)î - (2 m)j

B = (2 m)î – (4 m)I

A.B = { (1 m)î - (2 m)j } . { (2 m)î – (4 m)j }

A.B = (1×2) + {(-2) × (-4)} m

A.B = (2 + 8) m

A.B = 10 m