Lỗi đề r bn nhó:)))

20,21 x a + 20,1 x b + 20,2 x c + 79,79 x a + 79,9 x b + 79,8 x c

=20,21 x 20,21 + 20,1 x 20,21 + 20,2 x 20,21 + 79,79 x 20,21+ 79,9 x 20,21 + 79,8 x 20,21

= (20,21+ 20,1+ 20,2+79,79+79,9+79,8 ) x 20,21 

=                             300 x 20,21

=          6063

a) \(...=20,21.a+79,79a+20,1.b+79,9.b+20,2.c+79,8.c=100.a+100.b+100c=100.\left(a+b+c\right)\)

b) \(...\Rightarrow x+x+...+x+\left(1+2+...+100\right)=5750\)

\(\Rightarrow50x+50.51:2=5750\)

\(\Rightarrow50x+1275=5750\)

\(\Rightarrow50x=5750-1275\Rightarrow5x=4475\Rightarrow x=895\)

a,6030

b,x=7

bổ sung câu a) \(100.\left(a+b+c\right)=100.20,1=2010\)

ủa, ko trả lời mà vô hoại nguoif ta chi

a) = 1,7 x 46 + 1,7 x 60 + 1,7 x 94

     = 1,7( 46 + 60 + 94 )

     = 1,7 x 200 = 340

b) 202,1 x 3,6 +202,1 x6,3 +2021 : 100

= 202,1 x 3,6 + 202,1 x 6,3 + 20,1

= 202,1 x ( 3,6 + 6,3 + 0,1 ) 

= 202,1 x 10 

=2021

c)20,21 x 48 + 20,21 x 51 + 2021 : 100

= 20,21 x 48 + 20,21 x51 + 20,21

= 20,21 (48+51+1)

= 2021

HAPPY NEW YEAR !!!
Chúc bạn hok tốt :3

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=20,21*(4,8-3,7)-20,21

=20,21*1,1-20,21

=20,21*0,1

=2,021

20,21 x 65 + 34 x 20,21 + 20,21

= 20,21 x (65 + 34 + 1)

= 20,21 x 100

= 2021

Tính bằng cách thuận tiện nhất:

20,21 x 65 + 34 x 20,21 + 20,21

= 20,21 x ( 65 + 34 + 1 )

= 20,21 x 100

= 2021

Hok tốt

20,21 x 36 + 63 x 20,21 + 20,21

= 20,21 x 36 + 63 x 20,21 + 20,21 x 1

= 20,21 x ( 36 + 63 + 1)

= 20,21 x 100

= 2 021

20,21 x 36 + 63 x 20,21 + 20,21

= 20,21 x (36 + 63 + 1)

= 20,21 x 100

= 2021

`20,21xx109-20,21xx8-20,21`

`=20,21xx(109-8-1)`

`=20,21xx100=2021`

20,21 x 109 - 20, 21 x 8 - 20,21

= 20,21 x ( 109 - 8 - 1 )

=20,21 x 100 =2021

= 20,21 x (109 - 8 -1)

= 20,21 x 100

= 2021