2014 Tianjin Question 1 Single-choice Differentiating 2014_天津 Paper 1. i是虚数单位,复数 ${ \frac { 7 + i } { 3 + 4 i } } =$ A. 1-iB. $- 1 + i$C. ${ \frac { 1 7 } { 2 5 } } + { \frac { 3 1 } { 2 5 } } i$D. $- \frac { 1 7 } { 7 } + \frac { 2 5 } { 7 } i$ Answer keyA ☆ SaveCan't do it, show the explanation查看原卷 →