Thread: Complex no.s raised to exponents & divided...

Hi guys,

i have a problem...it goes like this:

Given: z1= 2,5+8i and z2= 0,5-3i

2) Now Calculate: (z1)^2/(z2)^3

This is what my answer looks like: -947,969/874,704 - 1309,438i/874,704

I need to know where i went wrong please?

Thanks in advance...

Originally Posted by Toyboy

Given: z1= 2,5+8i and z2= 0,5-3i

Now Calculate: (z1)^2/(z2)^3

This is what my answer looks like: -947,969/874,704 - 1309,438i/874,704

I need to know where i went wrong please?

Well, (5/2 + 8i)^2 = (160i - 231) / 4
and (1/2 - 3i)^3 = (198i - 107) / 8
SO:
[(160i - 231) / 4] / [(198i - 107) / 8] = (320i - 462) / (198i - 107)

Hope that helps...

But since you don't tell us what you did there is no way to say what, if anything, you did wrong!

Originally Posted by HallsofIvy

But since you don't tell us what you did there is no way to say what, if anything, you did wrong!

My apologies, this is what i did:

(2,5+8i)^2/(0,5-3i)^3
(2,5+8i)(2,5+8i)/(0,5-3i)(0,5-3i)(0,5-3i)

....mulitplied it all out and ended up with this: -947,969/874,704 - 1309,438i/874,704

Originally Posted by Toyboy

(2,5+8i)(2,5+8i)

Do you get what I got when you complete that one...see my previous post... ??

Originally Posted by Wilmer

Do you get what I got when you complete that one...see my previous post... ??

Sorry i missed your post...

Nope, it does not, mine equates to -1.084-1.497i
Your answer equates to 4.318+1.61(recurrring 61)

Sorry, but got no idea what you're talking about or doing...
mine equates to -57.75 + 40i ; or to -17.75 if 1 is used instead of i

I'll ask you once more:
I get: (2.5 + 8i)^2 = (160i - 231) / 4
What do you get: (2.5 + 8i)^2 = ?

Originally Posted by Toyboy

Given: z1= 2,5+8i and z2= 0,5-3i
2) Now Calculate: (z1)^2/(z2)^3
This is what my answer looks like: -947,969/874,704 - 1309,438i/874,704

Originally Posted by MaxJasper

Agree. (320i - 462) / (198i - 107) = ~2.226798 + ~1.129962 i