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`a)2018xx(1/2+1212/2424)`
`=2018xx(1/2+1/2)`
`=2018xx2/2=2018`
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`b)15xx2121/4343+15xx222222/434343`
`=15xx(2121/4343+222222/434343)`
`=15xx(21/43+22/43)`
`=15xx43/43=15`
\(\dfrac{181818}{212121}=\dfrac{181818:10101}{212121:10101}=\dfrac{18}{21}\)
\(\dfrac{18}{21}=\dfrac{18:3}{21:3}=\dfrac{6}{7}\)
Vậy \(\dfrac{181818}{212121}=\dfrac{6}{7}\) ta chọn C
15×2121/4343+15×222222/434343
= 15 x (21x101)/(101x43) + 15x(22x 10101)/(43x10101)
= 15 x 21/43 + 15 x 22/43
= 15x(21/43 + 22/43)
= 15x1 = 15
232323/434343=23/43=161/301
6/7=258/301
mà 161<258
nên 232323/434343<6/7
Bang 14,67750027 nha! 15x2121/4543 +15x222222/434343=4545/649+330/43=14,67750027. Chuc bn hoc tot
a: =4/5+1/5+2/3+1/3=1+1=2
b: =17/12+7/12+29/7-8/7=3+2=5
c: =3/5+2/5+16/7-1/7-1/7
=1+2=3
d: =2/5+3/5+2/3+1/3+7/4+1/4
=1+1+2
=4
=15(21/43+33/35)
=6462/301
cảm ơn