Question

Tính:

a) \(\overrightarrow{a}.\overrightarrow{b}\) với \(\overrightarrow{a}=\left(5;2;-4\right)\), \(\overrightarrow{b}=\left(4;-2;2\right)\).

b) \(\overrightarrow{c}.\overrightarrow{d}\) với \(\overrightarrow{c}=\left(2;-3;4\right)\), \(\overrightarrow{d}=\left(6;5;-3\right)\).

Answer 1

a) \(\overrightarrow a .\overrightarrow b  = 5.4 + 2.( - 2) - 4.2 = 8\)

b) \(\overrightarrow c .\overrightarrow d  = 2.6 - 3.5 + 4.( - 3) =  - 15\)