Question

If vectors 2i+4j-7k and 2i+6j+qk are perpendiculars then value of q is?

Answer 1

If vectors are perpendicular, their scalar producti is equal to zero. Thus, obtain the following equation:

$$2\cdot 2 + 4\cdot 6 -7\cdot q = 0\\ q = \dfrac{28}{7} = 4$$

Answer. 4.