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complex numbers

{(bi)/(1+ai)}-{(3b+4i)/(3a+b)} sove for a and b both are real numbers?
I think you might have miss typed it because you're lacking an equality in there. But just multiply by the denominators and solve the quadratic.
Reply 2
Jammy is right, you are missing some sort of equality in your question.
yh sorry the actual question is {(bi)/(1+ai)}-{(3b+4i)/(3a+b)}=0 solve for a and b both real?
Reply 4
Original post by Engineeringbeast
yh sorry the actual question is {(bi)/(1+ai)} - {(3b+4i)/(3a+b)}=0 solve for a and b both real?


multiply top and bottom with the conjugate pairs, and equate real and imaginary parts (or just multiply it out on both sides).
i managed to do that but once i reach this point i got confused. (3abi)+(b^2i)-(4i)+(4a^2i)=(3b)-(ab^2)
Reply 6
Original post by Engineeringbeast
i managed to do that but once i reach this point i got confused. (3abi)+(b^2i)-(4i)+(4a^2i)=(3b)-(ab^2)


i multiplied the equation on the left with 1-ai and then multiplied out the rest & got the following equations after equating real and imaginary parts:

4a2+4=3ab+b24a^2 + 4 = 3ab + b^2 imaginary

3a2b+ab2=3a2b+3b3a^2 b + ab^2 = 3a^2 b + 3b real

Edit: Now you can solve the two simultaneous equations to solve for a and b. If you're still stuck let me know.
(edited 10 years ago)
Original post by a10
i multiplied the equation on the left with 1-ai and then multiplied out the rest & got the following equations after equating real and imaginary parts:

4a2+4=3ab+b24a^2 + 4 = 3ab + b^2 imaginary

3a2b+ab2=3a2b+3b3a^2 b + ab^2 = 3a^2 b + 3b real

Edit: Now you can solve the two simultaneous equations to solve for a and b. If you're still stuck let me know.

TBH, I can't see a simple way to go from here.


Original post by Engineeringbeast
(3abi)+(b^2i)-(4i)+(4a^2i)=(3b)-(ab^2)

I found this to be done wrong.
Multiplying through the original equation with (1+ai)(3a+b) gives:
:3abi:+B^2i-3b:-3abi:-4i+4a=0
Separate real and imaginary and solve.
Reply 8
Original post by Jammy Duel
TBH, I can't see a simple way to go from here.


Why not?

You get a= 3/b sub it into the first equation you just get a quadratic equation which can factorise.
Original post by a10
Why not?

You get a= 3/b sub it into the first equation you just get a quadratic equation which can factorise.

point, still unnecessarily long winded and complicated in comparison :tongue:
Reply 10
Original post by Engineeringbeast

(bi)(1+ai)(3b+4i)(3a+b)=0\frac{(bi)}{(1+ai)}-\frac{(3b+4i)}{(3a+b)}=0 solve for a and b both are real numbers?


Thanks for the puzzle. I'm feeling a bit sleepy so will work on it in the morning.

Till then, enjoy this engineering-related poem:
[video="youtube;m-tmtezdpZ0"]https://www.youtube.com/watch?v=m-tmtezdpZ0[/video]

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