complex number

• Oct 29th 2008, 05:54 PM
boomshine57th
complex number
hey guys! just a quick how to find inverse 1/z? for the complex number
(-3-4i)

i know its very easy, but its really late and my brain has givven up on me. sorry :(

thank you
• Oct 29th 2008, 05:56 PM
Mathstud28
Quote:

Originally Posted by boomshine57th
hey guys! just a quick how to find inverse 1/z? for the complex number
(-3-4i)

i know its very easy, but its really late and my brain has givven up on me. sorry :(

thank you

Multiply by the conjugate $\displaystyle -3+4i$
• Oct 29th 2008, 05:59 PM
boomshine57th
the conjugate is -3+4i

so do i multiply (-3+4i)(-3-4i)

is that what u meant?

sorry if i sounds very stupid

thank you for helping me
• Oct 29th 2008, 06:00 PM
Mathstud28
Quote:

Originally Posted by boomshine57th
the conjugate is -3+4i

so do i multiply (-3+4i)(-3-4i)

is that what u meant?

sorry if i sounds very stupid

thank you for helping me

$\displaystyle \frac{1}{-3-4i}\cdot\frac{-3+4i}{-3+4i}$