a) 214 × 13 + 214 × 17 = 214 × (13 +17)

= 214 × 30

= 6420

b) 58 × 635 + 48 × 635 = (58 – 48 ) × 635

= 10 × 635

= 6350

c) 4 × 19 × 25 =100 × 19

= 1900

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

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

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

\(=214\times1000\)

\(=214000\)

= 745 x 214 + 254 x 214 + 214 x1

= 214 x ( 745 + 254 + 1)

= 214 x 1000

= 214000

Không có cách làm thuận tiện nhất

Chắc thế !

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? )}

214x{23-12}=214x11=2354

365x{49-39}=365x10=3650

a) 214 x 23 - 214 x 12 = 214 x (23-12) = 214 x 11 = 214 x 10 + 214 = 2140 +214 = 2354

b) 49 x 365 - 39 x 365 = 365 x (49-39) = 365 x 10 = 3650

a. 4125:15-405:15

   =(4125-405):15

   =3720:15

   =248.

b. 25x5x4x3

   = 25x4x5x3

   = 100x15

   =1500.

c. 236x20-36x20

   =(236-36)x20

   = 200x20

   =4000.

d) 785x214+215x214

= (785+215)x214

=  1000x214

=214000

A)  4125 : 15 - 405 : 15

=  ( 4125 - 405 ) : 15 = 3720 : 15 = 248

B)  25 x 5 x 4 x 3

=  ( 25 x 4 ) x ( 5 x 3 ) = 100 x 15 = 1500

C)  236 x 20 - 36 x 20

= ( 236 - 36 ) x 20 = 200 x 20 = 4000

D)  785 x 214 + 215 x 214

=  ( 785 + 215 ) x 214 = 1000 x 214 = 214 000

            Chúc bạn học tốt

\(\frac{17}{25}\times\frac{13}{19}+\frac{17}{25}\times\frac{6}{19}\)

\(=\frac{17}{25}\times\left(\frac{13}{19}+\frac{6}{19}\right)\)

\(=\frac{17}{25}\times\frac{19}{19}\)

\(=\frac{17}{25}\times1\)

\(=\frac{17}{25}\)

_HT_

\(\dfrac{17}{25}\left(\dfrac{13}{19}+\dfrac{6}{19}\right)\)

\(=\dfrac{17}{25}.1=\dfrac{17}{25}\)

1, 2x30+30+5x30+60=30x(2+1+5)+60=30x8+60=240+60=300

2,3059-213+214-87=(3059-87)+(214-213)=2972+1=2973

nha

1. 2 × 30 + 30 + 5 × 30 + 60

= 2 × 30 + 30 × 1 + 5 × 30 + 30 × 2

= 30 × ( 2 + 1 + 5 + 2 )

= 30 × 10

= 300

2. 3059 - 213 + 214 - 87

= ( 3059 - 87 ) + ( 214 - 213 )

= 2972 + 1

= 2973

Cbht

\(\dfrac{17}{20}\) x \(\dfrac{27}{13}\) + \(\dfrac{27}{13}\)  x \(\dfrac{3}{20}\)

= (\(\dfrac{17}{20}\)  + \(\dfrac{3}{20}\)) x \(\dfrac{27}{13}\)

= 1 x \(\dfrac{27}{13}\)

=\(\dfrac{27}{13}\)

Tick cho mik nha