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Mathematics 7 Online
OpenStudy (anonymous):

(1+i)/(1-i); solve

OpenStudy (anonymous):

would it be -i?

zepdrix (zepdrix):

The product of conjugates normally gives you the DIFFERENCE of squares. Example: \[(a+b)(a-b)=(a^2-b^2)\] But with complex numbers, since you're squaring the imaginary unit "i", you end up with the SUM of squares instead! Example: \[(a+bi)(a-bi)=(a^2+b^2)\]

zepdrix (zepdrix):

If you're still confused you can let me know c:

OpenStudy (anonymous):

is it A. -i ? B. 1 C. or i

zepdrix (zepdrix):

It is.... none of those... :O

OpenStudy (anonymous):

is it -1 ?

zepdrix (zepdrix):

Hmmm it should be +2.. that's not an option? Hmm lemme look again.. maybe I made a silly mistake somewhere.

OpenStudy (anonymous):

does it make a difference if it says simplify instead

zepdrix (zepdrix):

hmmm

OpenStudy (anonymous):

because then it is probs -i

zepdrix (zepdrix):

OH AHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH

zepdrix (zepdrix):

your problem is division, I didn't see the division symbol.. sorry that text is REALLY hard to read.

zepdrix (zepdrix):

\[\frac{ 1+i }{ 1-i }\] so ummm, to rationalize this, we'll multiply the top and bottom by the CONJUGATE of the bottom. so multiply it by (1+i)/(1+i)

zepdrix (zepdrix):

\[[1^2-(i)^2]=[1-(-1)]=(1+1)=2\] The bottom will simplify nicely like this.

zepdrix (zepdrix):

Top gives us this: \[(1+i)(1+i)=1^2+2i+i^2\]

OpenStudy (anonymous):

here.

zepdrix (zepdrix):

\[1^2+2i+i^2=1+2i+(-1)=2i\]\[\large \frac{ 2i }{ 2 }=i\]

OpenStudy (anonymous):

so D?

zepdrix (zepdrix):

Dude try to put in some effort lol.... sheesh :\

OpenStudy (anonymous):

just making sure

zepdrix (zepdrix):

Yah D sounds right, I think :O

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