gaokao 2015 Q2

gaokao · China · national-II-science 5 marks Complex Numbers Arithmetic Systems of Equations via Real and Imaginary Part Matching

If $a$ is a real number and $(2 + \mathrm { ai})(a - 2\mathrm{i}) = -4\mathrm{i}$, then $a =$
(A) $-1$
(B) $0$
(C) $1$
(D) $2$

If $a$ is a real number and $(2 + \mathrm { ai})(a - 2\mathrm{i}) = -4\mathrm{i}$, then $a =$

(A) $-1$

(B) $0$

(C) $1$

(D) $2$