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karnten07
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Homework Statement
Let F be a field. For any a,b [tex]\in[/tex] F, b[tex]\neq[/tex]0, we write a/b for ab^-1. Prove the following statements for any a,a' [tex]\in[/tex]F and b,b' [tex]\in[/tex] F\{0}:
i.) a/b = a'/b' if and only if ab' = a'b.
ii.) a/b + a'/b' = (ab' + a'b)/bb'
iii.) (a/b)(a'/b') = (aa')/(bb')
iv.) ((a/b)/(a'/b')) = (ab')/(a'b) if in addition a' [tex]\neq[/tex] 0
Homework Equations
The Attempt at a Solution
Okay I am getting really confused in these questions because i don't know when it means to divide by and when it is showing that a/b = ab^-1
i.) want to show a/b = a'/b' if and only if ab' = a'b.
from ab' = a'b a = a'b/b' and a' = ab'/b
So substituting in values of a and a'
a/b = (a'b/b')/(ab'/b)
Carrying out division:
(a'ba')/(b'ab') and because a'b = b'a, substitute this in and cancel like terms:
(ab'a'/ab'b') = a'/b'
therefore a'/b' = a/b
is this even right because its just rearranging stuff?
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