# complex numbers rectangular form

• Aug 12th 2009, 04:20 PM
Jonny-123
complex numbers rectangular form
how do i express the following in rectangular form?

-3+5i+(7+4i)/(1+2i)

thankyou,
• Aug 12th 2009, 04:38 PM
skeeter
Quote:

Originally Posted by Jonny-123
how do i express the following in rectangular form?

-3+5i+(7+4i)/(1+2i)

thankyou,

$-3+5i + \frac{7+4i}{1+2i} \cdot \frac{1-2i}{1-2i}$

multiply the ratios and simplify.
• Aug 12th 2009, 04:47 PM
Plato
Quote:

Originally Posted by Jonny-123
how do i express the following in rectangular form?
-3+5i+(7+4i)/(1+2i)

Which is it $- 3 + 5i + \frac{{7 + 4i}}{{1 + 2i}}\text{ or }\frac{{( - 3 + 5i)(7 + 4i)}}{{1 + 2i}}$?

In any case
$\frac{1}{z} = \frac{{\overline z }}{{\left| z \right|^2 }}$