Math, asked by namku, 1 year ago

i need an explanation of how ror^-1 was derived from the above 2 sets

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Answered by rational
2
R=\{(1,3),(1,5),(2,3),(2,5),(3,5),(4,5)\}

Get R^{-1} by swapping coordinates :
R^{-1}=\{(3,1),(5,1),(3,2),(5,2),(5,3),(5,4)\}

the composition R\,\circ\,R^{-1} can be obtained by seeing the possible points of R for each value of R^{-1} :
 R^{-1}(3)=1,2\implies\,R\,\circ\,R^{-1}(3)=R(1),R(2)=3,5

that means, the composition R\,\circ\,R^{-1} maps 3 to 3 or 5. therefore you get points (3,3) and (3,5)

rational: what are the values of R^(-1)(5) ?
rational: simply look at R^(-1) row, 5 is getting mapped to 1,2 yes ?
rational: that means R^(-1)(5) = 1 or 2
namku: u said to see posiible points of r for each value of r inverse but r inverse of 5 doesnt have any points in r
rational: we need to see where 1, 2 are getting mapped to in R
rational: 5 ------>R^(-1)------->1 or 2-------R-------> 3 or 5
rational: therefore RoR^(-1)(5) = 3 or 5
rational: and you get points (5, 3) and (5, 5)
namku: got it thanks a lot
rational: np:)
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