Let $( 1 + 2 \mathrm { i } ) a + b = 2 \mathrm { i }$ , where $a , b$ are real numbers, then A. $a = 1 , b = - 1$ B. $a = 1 , b = 1$ C. $a = - 1 , b = 1$ D. $a = - 1 , b = - 1$
Let $( 1 + 2 \mathrm { i } ) a + b = 2 \mathrm { i }$ , where $a , b$ are real numbers, then
A. $a = 1 , b = - 1$
B. $a = 1 , b = 1$
C. $a = - 1 , b = 1$
D. $a = - 1 , b = - 1$