# Linear algebra, polar coordinate problem.

• Mar 16th 2008, 05:58 PM
LostInCalculus
Linear algebra, polar coordinate problem.
Find all solutions for $\displaystyle x^2-3x+5$ and express them in the form a+bi.

I dont really have a clue, I used the quadratic formula and got $\displaystyle (3+(-11)^(1/2))/2$ and $\displaystyle 3-(-11)^(1/2)/2$. From there I am totally clueless as to how to get to a+bi form.

Can anyone help?
• Mar 16th 2008, 06:23 PM
mr fantastic
Quote:

Originally Posted by LostInCalculus
Find all solutions for $\displaystyle x^2-3x+5$ and express them in the form a+bi.

I dont really have a clue, I used the quadratic formula and got $\displaystyle (3+(-11)^(1/2))/2$ and $\displaystyle 3-(-11)^(1/2)/2$. From there I am totally clueless as to how to get to a+bi form.

Can anyone help?

$\displaystyle \frac{3 \pm \sqrt{-11}}{2} = \frac{3 \pm i\, \sqrt{11}}{2} = \frac{3}{2} \pm i\, \frac{\sqrt{11}}{2}$ !!
• Mar 16th 2008, 06:58 PM
LostInCalculus
Wow, one of those simple things that you just gotta know.

Thanks alot! (Clapping)