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Mathematics 17 Online
OpenStudy (anonymous):

How would i rationalize 6/ 3+i

OpenStudy (anonymous):

multiply by the conjugate

OpenStudy (anonymous):

multiply by 1 using the conjugate*

OpenStudy (anonymous):

* top n bottom by 3-i

OpenStudy (anonymous):

So 9i?

OpenStudy (anonymous):

6(3-i) / (3+i)(3-i)

OpenStudy (anonymous):

Is that all that I have to do? I'm not really sure how to do these sorts of problems

OpenStudy (anonymous):

You need to multiply out the brackets and simplify if possible

OpenStudy (anonymous):

Just like normal except you have i's to deal with...

OpenStudy (anonymous):

6(3-i)? Wouldn't the bottom cancel itself out?

OpenStudy (anonymous):

It is a kind of trick to get rid of the i on the bottom.....

OpenStudy (anonymous):

Similar to how you get rid of a rdical, same sort of idea...

OpenStudy (anonymous):

So confused

OpenStudy (anonymous):

Multiply it out and you will see...

OpenStudy (anonymous):

9-i/9

OpenStudy (anonymous):

which you could divide 9 by 9 to get one, so -i?

OpenStudy (anonymous):

6(3-i) is 18-6i Where do you get 9-i from?

OpenStudy (anonymous):

Oh wow opps. haha I added.

OpenStudy (anonymous):

Ok, now what do you get for the bottom?

OpenStudy (anonymous):

9?

OpenStudy (anonymous):

You have (3+i)(3-i) Tell me how it comes to 9

OpenStudy (anonymous):

You multiply and the +i and -i cancel out? i'm really sorry, this is new to me haha

OpenStudy (anonymous):

(3+i)(3-i) is 3*3 + 3*i -3*i - i^2 (using FOIL?)

OpenStudy (anonymous):

So the 3i's cancel out and leave 9-i^2 So what is i^2 ?

OpenStudy (anonymous):

-1

OpenStudy (anonymous):

Right, so what is the bottom ( hint-it is not 9)

OpenStudy (anonymous):

8?

OpenStudy (anonymous):

9-(-1)

OpenStudy (anonymous):

10

OpenStudy (anonymous):

Ok so finally you have 18-6i/10 which you can divide by 2 to get 9-3i/5 as a final answer.

OpenStudy (anonymous):

So, procedure for these is *by conjugate top and bottom then simplify

OpenStudy (anonymous):

thank you so much!!!

OpenStudy (anonymous):

ur welcome

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