I need solve this question MCQ of calculus III

Question 3 Question 4 Not yet answered Not yet answered Marked out of 5.00 Marked out of 5.00 Flag question Flag question If the vectors a and b are such that a = kb If a = 2j and b = 4k, then a . b = 8. where k is a positive scalar, then the vectors a and b are parallel vectors which are in the opposite direction. Select one: O True Select one: O True OFalse O False Question 7 Question 8 Not yet answered Not yet answered Marked out of 5.00 Marked out of 5.00 Flag question Flag question If a = (-1, 1, 2) and b = (1, 3, 1), then Which of the following pair of vectors have the which of the following gives la - b|? same direction? Select one: Select one: O a = -i - 2j + 2k and O V9 b = +3i + 8j + 6k. 0 -V9 O a = 5i - 4j + 3k and O (-2, -2, 1) b = 15i - 12j + 9k. O a = 3i and b = -4i. None of them. O a = -6i - 2j - 4k and O (2, 2, -1) b = -15i + 5j + 10k. O None of them