$#Dino$
Câu 1:
a) `-270/450=(-270:90)/(450:90)=-3/5`
b) `-26/-156=(-26:(-26))/(-156:(-26))=1/6`
c) `(2xx5xx13)/(26xx35)=(2xx5xx13)/(2xx13xx5xx7)=1/7`
d) `49+7xx49/49`
`=49+7xx1`
`=49+7`
`=56`
........................
Câu 2:
a) `-7/10 ; 1/33`
`-7/10=(-7.33)/(10.33)=231/330`
`1/33=(1.10)/(33.10)=10/330`
..................
b) `-5/10 ; 3/20 ; 9/70`
`-5/10=(-5.14)/(10.14)=-70/140`
`3/20=(3.7)/(20.7)=21/140`
`9/70=(9.2)/(70.2)=18/140`