Vector inner product operation | a | = 3. | B | = 4 = 60 ° to find (a + 2b). (a-b)

Vector inner product operation | a | = 3. | B | = 4 = 60 ° to find (a + 2b). (a-b)

ab=|a|*|b|cos60°=6
(a+2b).(a-b)
=a²-ab+2ab-2b²
=a²+ab-2b²
=9+6-32
=-17