A • B = (2i + 5j − 4k) • (−2i − 3j − 5k) = (2 × -2) + (5 × -3) + (-4 × -5) = -4 + -15 + 20 = 1
A • B
= (2i + 5j − 4k) • (−2i − 3j − 5k)
= (2 × -2) + (5 × -3) + (-4 × -5)
= -4 + -15 + 20
= 1