Answer:
z = ± 3i
Step-by-step explanation:
note that [tex]\sqrt{-1}[/tex] = i
Given
z² + 9 = 0 ( subtract 9 from both sides )
z² = - 9 ( take the square root of both sides )
z = ± [tex]\sqrt{-9}[/tex] = ± [tex]\sqrt{9(-1)}[/tex] = ± [tex]\sqrt{9}[/tex] × [tex]\sqrt{-1}[/tex] = ± 3i
