Problem in Complex Number Question (2 Viewers)

[vkay]

This questions seems really easy... but for some reason I just can't figure it out!!

Simplify (4a+16ib) / (12b-3ia) where a, b E lR

However, I'm not allowed to multiply top and bottom by the conjugate of the denominator.

Please help! Thanks!!!

 

[Grey Council]

why can't you multiply by the conjugate of the bottom?

 

[vkay]

because I'm supposed to simplify it two ways...and I've already completed one way by multiplying the conjugate... so I have to find another way.

 

[Xayma]

There is a way to divide complex numbers you probably covered it early in the course, but it is alot easier to use conjugates.

 

[vkay]

Yeah, I know... which is why I used the conjugate method first. But I don't know any division method using cartesian equations. I tried to turn it into mod-arg form so that division could be easier...but then it was really messy (and frankly didn't work) so...

 

[Grey Council]

hokay, turn them into a pair of ordered numbers, then divide.

 

[vkay]

what are ordered numbers?

 

[Xayma]

Hmm just thinking but could you do (4a+16ib)(12b-3ia)^-1

Would that work after you do the funky stuff or not?

 

[:: ck ::]

prior questoin ... aiii ... ur meant to do this durin workshops...

ill get u started

think "division of complex numbers in mod-arg form"
i.e : z1/z2 = r1/r2 cis (@1-@2)

if u still cant do it ill scan the answer if ur nice

 

[Avicenna]

Here's the solution....

 

[Heinz]

Originally posted by Avicenna
Here's the solution....

Do you use a maths program to make those symbols?

 

[ae]

(4a+16ib) / (12b-3ia)

= 4(a+4ib)/ -3i(a+4ib)

= -4/3i * i/i

= 4i/3

 

[:: ck ::]

mmm heres the other method....

use ur division of complex number rules


edit : avicenna how can u simplify it to pi/2 without explanation~

 

[lost fortian]

Awesome!!!

Avicenna: How did you get to pi/2 straight away?

 

[Avicenna]

This is how i got pi/2....

 

[Avicenna]

Originally posted by Heinz
Do you use a maths program to make those symbols?

Actually i do use microsoft equation found in your word processor (Microsoft Word)

Click on the Insert button then click on object..a list of all programs that allow you to insert objects would come up..search for microsoft equation then away you go...

Another program is MathType

 

[Mill]

This is what your workshop tutor is for. Or even your class tutor if you need a hint or something. I guess you aren't a Bondi student, and I don't recognise the hand-writing. You will get more gain from these questions if you try them yourselves rather than having people give you full solutions to them...

 

[Mill]

Avicenna made a mistake anyway.

And there's actually at least 4 ways to do the question.

 

[martin310015]

for this question i used the mod arg form and got stuck in the angle part.....didn't know what to do.

 

[:: ck ::]

just draw up a right angled triangle to simplify...