Q68. If the vectors a = 2i + 3j - 4k and b = αi + 9j + 5k are perpendicular, what is the value of α?Mathematics — NUST Mock 6 — Question 68 of 200A. 7B. -7/2C. -7D. 7/2Practice more Mathematics MCQs for entrance exam preparation on Examora.io.← Previous Question Next Question →