Stop guessing! Show us how you arrived at either of those answer, please.
I will point out that whether you say
e^{5\pi/4}= \frac{1- i}{-\sqrt{2}}[/itex]<br />
or<br />
e^{3pi/4}= \frac{1- i}{-\sqrt{2}}[/itex]<br />
You run into the rather sizeable difficulty that the number on the left of the equal sign is real while the number on the right is not!<br />
<br />
Is it at all possible that you <b>meant</b> e^{5\pi i/4} and e^{3\pi i/4}?