Final answer:
The expression of the complex number √−9 in terms of j is 3j, as j represents √−1 in engineering.
Step-by-step explanation:
To express the given complex number √−9 in terms of j, we must first recognize that j is typically used in engineering fields and represents the imaginary unit, which is the same as i in mathematics. Remember that i or j is defined as the square root of -1. Therefore, the square root of -9 can be written as:
√−9 = √(9 × -1) = √9 × √−1 = 3i or 3j
So, the expression of √−9 in terms of j is 3j.