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Mathematics 17 Online
OpenStudy (anonymous):

simplify: 8/2+2i

OpenStudy (anonymous):

is this \[\frac{8}{2+2i}\]

OpenStudy (anonymous):

yes :)

OpenStudy (anonymous):

so first, learn to write it correctly. if you are dividing by a sum, enclose it in parentheses... 8/(2+2i) is the correct way or as i did it in equation editor. now, to solve, multiply the top and bottom by the conjugate of the denominator.

OpenStudy (anonymous):

i would divide the top and bottom from 2+2i & i will get 16+16i / 4+12i^3?

OpenStudy (anonymous):

no, multiply top and bottom by the conjugate of the denominator. the denominator is 2+2i, right? so what is its conjugate?

OpenStudy (anonymous):

isnt it the same?

OpenStudy (anonymous):

so the copnjugate would be 2-2i?

OpenStudy (anonymous):

yes it is!

OpenStudy (anonymous):

so now i just multiply it by the top and bottom?

OpenStudy (anonymous):

you got it! tell me what you get.

OpenStudy (anonymous):

16-16i/ 4-4i

OpenStudy (anonymous):

nope. \[\frac{ 8 }{2+2i }=\frac{ 8 }{2+2i }\cdot\frac{ 2-2i }{2-2i }=\frac{ 16-16i }{4-4i+4i-4i^2 }=\frac{ 16-16i }{4-4i^2 }\] and \(i^2 = -1\), right? so put that in and see what you get.

OpenStudy (anonymous):

16-16i/ 4+4 = 16-16i/ 8

OpenStudy (anonymous):

yes and then simplify

OpenStudy (anonymous):

and again, use the parentheses... it should be (16-16i)/8

OpenStudy (anonymous):

4-4i/ 2

OpenStudy (anonymous):

parentheses? and is it completely simplified?

OpenStudy (anonymous):

(2-2i)/1

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