\(a)15.\left(\dfrac{212121}{434343}+\dfrac{333333}{353535}\right)\)

\(=15.\left(\dfrac{21}{43}+\dfrac{33}{35}\right)\)

\(=15.\dfrac{2154}{1505}\)

\(=\dfrac{6462}{301}\)

a)=15.(21/43+33?55)=15.234/215=16 14/43
b)=328.412-412+400/328.412-12=328.412-12/328.412-12=1
c)7217721 hay là 721721 vậy?
 

A)15x2154/1505

=6462/301

B)=103/1031

C)=327/328+400/-12

=727/316

D)=4/5

Bai 2=4 ta thay mau so la 4 nen 43-4=39 va 56-4=52 ta se thay 39/52=3/4.

Giải chi tiết ra chứ

c 212121/353535

=212121:21/353535:35

=10101/10101

=212121:10101/353535:10101

=21/35

1-212121/353535=141414/353535=10101/353535

1-131313/141414=10101/141414

Vì

10101/141414>10101/353535

Nên

212121/353535>131313/141414

1/ Ta có : \(\frac{212121}{353535}=\frac{3.7.10101}{5.7.10101}=\frac{3}{5}=\frac{42}{70}\)

\(\frac{131313}{141414}=\frac{13.10101}{14.10101}=\frac{13}{14}=\frac{65}{70}\)

Vì 42 < 65 =>  \(\frac{42}{70}<\frac{65}{70}\)  =>  \(\frac{212121}{353535}<\frac{131313}{141414}\)

1)Ta có : 212121/353535 = 212121:10101/353535:10101 = 21/35 = 3/5

131313/141414 = 131313:10101/141414:10101 = 13/14

Ta có : 3/5 = 42/70 ; 13/14 = 65/70

Vì 42<65 => 42/70<65/70 => 212121/353535<131313/141414

2)Ta có : 2012/2013<1 

2013/2014<1

2014/2015<1

=> 2012/2013+ 2013/2014+ 2015/2012<1+1+1=3

Vậy 2012/2013+ 2013/2014+ 2015/2012<3

Ai chơi truy kích cấp cao thì kết bạn nha !!!!!!!!