This answer is equal to $\displaystyle{9}{i}\usepackage{cmbright}\Huge\$ , but it is not written as a complex number. A complex number is any number in the form $\displaystyle{a}+{b}{i}\usepackage{cmbright}\Huge\$ where a and b are real numbers. The correct answer is $\displaystyle{0}+{9}{i}\usepackage{cmbright}\Huge\$ .