Question

Simplify and write your answer in the form a+bi.

10/1+2i (this is a fraction)

Answers:

A. 10-20i/5
B. 2-4i
C. 1-2i
D. 10+5i

Answer 1

`(10)/(1+2i)\\\\\\=(10(1-2i))/((1+2i)(1-2i))\\\\\\=(10-20i)/(1 - (2i)^2)\\\\\\=(10-20i)/(1+4)~~~~~;[i^2 =-1]\\\\\\=\frac{10-20i}5\\\\=\frac{10}5 - \frac{20i}5\\\\=2-4i`