a: =20x71=1420

Hướng dẫn giải:

a) 280 x 71 : 14 = (280 : 14) x 71 = 20 x 71 = 1420

b) 125 x 88 : 11 = 125 x (88 : 11) = 125 x 8 = 1000

a) 35 x 2 x 9 x 5

= (35 x 9) x (2 x 5)

= (35 x 10 - 35) x 10

= (350 - 35) x 10

= 315 x 10 = 3150

b) 24 x 71 + 71 x 75 + 71

= 71 x (24+75+1)

=71 x 100

= 7100

giúpppppppppppppppppppppppppppppppppppp

=346x100=34600

=346x(28+71)

=346x99

=34254

= 346 x (28 + 71)

= 346 x 99

= 34254

                                               Bài giải 

a) 280 :  14 x 71= 20 x 71 = 1420

b)125 x 88: 11= 125 x ( 88: 11)= 125 x 8 = 1000

Nhớ k cho mình đó nnha!

\(a,280\times71:14=280:14\times71=20\times71=1420\)

\(b,125\times88:11=125\times\left(88:11\right)=125\times8=1000\)

\(\dfrac{9}{14}\times1+\dfrac{9}{14}\)

\(=\dfrac{9}{14}\times1+\dfrac{9}{14}\times1\)

\(=\dfrac{9}{14}\times\left(1+1\right)\)

\(=\dfrac{9}{14}\times2\)

\(=\dfrac{18}{14}=\dfrac{9}{7}\)

a) \(437\times136-437\times125\)

\(=437\times\left(136-125\right)\)

\(=437\times11\)

\(=4807\)

b) \(2009\times71+29\times2009\)

\(=2009\times\left(71+29\right)\)

\(=2009\times100\)

\(=200900\)

a) 437 x 136 - 437 x 125

= 437 x (136 - 125 )

= 437 x 11

=  4807

b) 2009 x 71 + 29 x 2009

= 2009 x ( 71 + 29 ) 

= 2009 x 100

= 200900

a) 437 x 136 - 437 x 125

  = 437 x (136 - 125)

  = 437 x 11

  = 4807

b) 2009 x 71 + 29 x 2009

   = 2009 x (71 + 29)

   =2009 x 100

   =200900

                                                  nhớ nha!

=25/56*14

=25/4

\(2,5:5,6\times14=2,5\times14:5,6=35:5,6=6,25\)