Final answer:
The question does not provide enough information to determine the value of 'k'. Additional context or details on the vectors involved are needed to solve for 'k'.
Step-by-step explanation:
The question asked does not provide sufficient details to determine the value of 'k' directly from the information given. The notation 'AB = (b - a)' suggests vector subtraction where vector AB is the result of subtracting vector 'a' from vector 'b'. However, no specific values or further context is presented in the question that would allow the calculation of 'k'. We would need additional information about vectors 'a' and 'b', or about the vector equation involving 'k', to find a numerical answer. When dealing with vector problems, it's important to have all the necessary vector components or magnitudes to solve for an unknown variable like 'k'.
If you can provide more information or clarify the vector equation involving 'k', I would be happy to assist further. Without additional context, the value of 'k' cannot be determined from the information presented in the question.