Answer:
33i - 12
Step-by-step explanation:
[tex]8i - (12 - 4i) + 7 \sqrt{ - 9} \\ = 8i - 12 + 4i + 7 \sqrt{9 \times ( - 1)} \\ = 12i - 12 + 7 \times 3 \sqrt{ - 1} \\ = 12i - 12 + 21i \: \: ( \because \sqrt{ - 1} = i)\\ = 12i + 21i - 12 \\ \therefore \red{ \bold{8i - (12 - 4i) + 7 \sqrt{ - 9} }= \purple{ \bold{33i - 12}}}[/tex]
