mk nghĩ là c 

chứ mk lười nghĩ :))))))

\(2733+x=4727\)

\(\Rightarrow x=4727-2733\)

\(\Rightarrow x=1994\)

\(8200-y=5700\)

\(\Rightarrow y=8200-5700\)

\(\Rightarrow y=2500\)

\(\Rightarrow x+y=1994+2500=4494\)

Vậy chọn đáp án \(C\)

C.4494

=214x100=21400

( 214 x 3 ) + ( 35 + 63 + 2 ) = 642 + 100

                                             = 742

214*6+3*214+214*2-214

=214*(6+3+2-1)

=214*10

=2140

~HT~ (Kick cho mik nha!!!)

214 x 6 + 3 x 214 + 214 x 2 - 214

214 x ( 6 + 3 + 2 - 1 )

214 x 10

2140

214 x(6 + 3) +428-214

214 x 9 + 214

1928 + 214

2142

\(\left(x+1\right)+\left(x+2\right)+...+\left(x+214\right)=23632\)

\(\Rightarrow\left(x+x+.....+x\right)+\left(1+2+....+214\right)=23632\)

\(\Rightarrow214x+23005=23632\)

\(\Rightarrow214x=627\)

\(\Rightarrow x=\frac{627}{214}\)

\(745\times214+254\times214+214\)

\(=214\times745+214\times254+214\times1\)

\(=214\times\left(745+254+1\right)\)

\(=214\times1000\)

\(=214000\)

= 745 x 214 + 254 x 214 + 214 x1

= 214 x ( 745 + 254 + 1)

= 214 x 1000

= 214000

745 x 214 + 254 x 214 + 214 x 1

214 x (745 + 254 + 1 )

214 x 1000

214000

4/21

D 4/21

a: =214*(13+17)=214*30=6420

b: =635(58-48)=635*10=6350

c: =100*19=1900

d: =4*32=128

= 214x(13+17)

=214x 30

=6420

214 x 13 + 214 x 17 = 214 x (13 + 17) = 214 x 30 = 6420

214 x 13 + 214 x 17

=214 x (13+17)

=214 x30

=6420

a) \(4\times378\times25\)

\(=\left(25\times4\right)\times378\)

\(=100\times378\)

\(=37800\)

b) \(214\times53-214\times45\)

\(=214\times\left(53-45\right)\)

\(=214\times8\)

\(=1712\)

a) \(4\times378\times25\)

\(=4\times25\times378\)

\(=100\times378\)

\(=37800\)

b) \(214\times53-214\times45\)

\(=214\times\left(53-45\right)\)

\(=214\times8\)

\(=1712\) _{( Thuận tiện chỗ nào? )}

a} 37800

b| 1712