`a,`
Ta có:
`2/-3 = (2 . (-5))/(-3 . 5) = (-10)/15`
`(-3)/5 = (-3 . 3)/(5.3) = (-9)/15`
Do `(-9)/15 > (-10)/15`
`=> (-3)/5 > 2/-3`
`b,`
Ta có:
`18/-50 = (18 . (-1))/(-50 . (-1)) = (-18)/50`
Do `(-17)/50 > (-18)/50`
`=> (-17)/50 > 8/-50`
`c,`
Ta có:
`1313/1818 = (1313 : 101)/(1818 : 101) = 13/18`
`131313/181818 = (131313 : 10101)/(181818 : 10101) = 13/18`
Do `13/18 = 13/18`
`=> 1313/1818 = 131313/181818`
`d,`
Ta có:
`1991/2020 < 1`
`2020/1991 > 1`
`=> 1919/2020 < 2020/1991`
`a,`
2/-7 = (2.(-11))/(-7 . (-11)) = (-22)/77`
`(-3)/11 = (-3 . 7)/(11 . 7) = (-21)/77`
Do `(-22)/77 < (-21)/77`
`=> 2/-7 < (-3)/11`
`b,`
Ya có:
`17/-34 = (17 . (-1))/(-34 . (-1)) = (-17)/34`
Do `(-17)/34 > (-17)/35`
`=> 17/-34 > (-17)/35`
`c,`
Ta có:
`101010/212121 = (101010 : 10101)/(212121 : 10101) = 10/21`
`1010/2121 = (1010 : 101)/(2121 : 101) = 10/21`
Do `10/21 = 10/21`
`=> 1010101/212121 = 1010/2121`
`d,`
Ta có:
`2012 . 2012 > 2002 . 2022`
`=> 2012/2002 > 2022/2012`
