tolong dijawab secepatnya ya!!

1||

a . b
= [-4 7] . [5 2]
= (-4)(5) + (7)(2)
= -20 + 14
= -6

2||

AB = b - a
AB = [1 3] - [4 -2]
AB = [-3 5]

BC = c - b
BC = [-3 2] - [1 3]
BC = [-4 -1]

Maka...
AB . BC
= [-3 5] . [-4 -1]
= (-3)(-4) + (5)(-1)
= 12 - 5
= 7