complex No. (1 Viewer)

[chousta]

hey all,

i got afew sheets for holidays but they dont have answers on them.

could somone post up some answers so that i can check.
with workin just in case i slipt up.

 

[bos1234]

question 1

Question 2:

argh hold on.. i got a mistake on question 2.....!!!!!!!.... b= -3... so the answer will b 3-2i or -2+i



Did u get the same answers as me..

answeers for the other 2 qns are
3-6i or 1+2i and last one
3-i pr -2+5i

goodluck with the rest of ur work bye

 

[chousta]

hey mate,

i got the same as you for the first 2 answers but didnt get the same as you for the last 2

could u post up ur workin?

 

[bos1234]

hmm last question.. was ur answer

7+9i/2 and -5-i/2
something like that??

LAST QUESTION...

 

[ih8skool]

for the 3rd and 4th question use the formula as above

If you get a^4 + bx^2 + c and cant factorise it
Let x=a^2 as above and then use the quadratic formula to find x

x=a^2

 

[chousta]

for the 3rd and 4th question use the formula as above

If you get a^4 + bx^2 + c and cant factorise it
Let x=a^2 as above and then use the quadratic formula to find x

x=a^2

lol??? that wasnt very valueable input......




to bos1234...yea i got that

 

[bos1234]

ok

 

[chousta]

Hey all,

whats the best and quickest way to prove this.

 

[dr baby beanie]

Use Demoivre's Theorum, but it says prove so it could be a longer different way

 

[haque]

z1/z2=(r1cisa/r2cisb)=cis(-b)/cis(-b) * (r1cisa/r2cisb) and then expanding and simplifying using the properties of cosine u get the required answr.

 

[dr baby beanie]

I sort of get it haque's way but why can't it be done by using Demoivre's Theorum, is it because it's a 'prove'?

ps sorry for invading ur question chousta

 

[chousta]

Hey all i have another question from my holiday worksheets.

Could u please post up your working, because all i have is the question, and incase i stuff up working helps.

 

[bos1234]

Thats Sir Jim Coroneos' handwriting

-----------------------------------

z+z^1 = (1-i)/(2+i) + (2+i)/(1-i)

cross multiply etc and simplify

= 3+2i/(3-i)

realising the denominator

=7+9i/10

therefore Re(z) = 7/10
Im(z)=9/10

 

[chousta]

Thats Sir Jim Coroneos' handwriting

not sure mate, got it on a sheet...

should i go and get his book??

 

[bos1234]

not sure mate, got it on a sheet...

should i go and get his book??

If you want to get good marks and appreciate the beauty of maths then yes you should get it.

Otherwise i dont reccomend it

-------------------------------------------------

Coroneos > cambridge

 

[chousta]

ahahah..... well said... its jsut that im getting it at school, and i dont really want to spend money on one. I think ill just wait till tuesday

 

[bos1234]

ur school is quite wealthy

 

[chousta]

ur school is quite wealthy

ahahah no..... i go to public.....they r very old and crappy....so i might just buy one.

 

[bos1234]

k
did you get similar working out for the 1st question?

 

[dr baby beanie]

I know how to do it DT's way except I'm not sure of slidely's way and unsure of the 'cosine properties' in haques way.

Would you like me to post up my working for the way I did it?