Answer:
36
Step-by-step explanation:
We are dealing with imaginary numbers, which works differently than a normal problem.
Let's combine (9i) and (i^2) and create a multiplication problem,
9ii^2 * 4i
Multiply the constants :
[tex]36i^2ii[/tex]
We see 4 i's in this problem, add them all together :
[tex]36i^4[/tex]
4 i's are equal to 1, now multiply the constant :
[tex]36 * 1[/tex]
36
