A. - 279.    B. -170.      C. -4600.      D. -4200

tich mik mik tich lai cho!

1945

a.$17\cdot (29-(-111\left)\right]+29\cdot (-17)$ 

$=17\cdot (29+111)-29\cdot 17$

$=17\cdot (29+111-29)$

$=17\cdot (29-29+111)$

$=17\cdot 111$

$=2997$

b.$19\cdot 43+(-20)\cdot 43-(-40)$

$=19\cdot 43-20\cdot 43+40$

$=43(19-20)+40$

$=43\cdot (-1)+40$

$=-43+40$

$=-3$

 [ chúc bạn học tốt ]

\(\left(29-9\right).\left(-9\right)+\left(-13-17\right).21\\ =20.\left(-9\right)+\left(-30\right).21\\ =\left(-180\right)+\left(-630\right)\\ =-810\)

= 20.(-9) + (-20) .21

= 20 .(-9 ) + 20 . (-21)

= 20 . (-9-21)

= 20 . (-30 )

=(-60)

a)  -(2016 + 39 + 17) - (-39 - 17)

= -2016 - 39 - 17 + 39 + 17 = -2016

b)  422 + (-85) + 278 - (-55)

= (422 + 278) - (85 - 55)

= 700 = 30 = 670

c)  28 x (29 - 23) - 29 x (28 - 23)

= 28x29 - 28x23 - 29x28 + 29x23

=23 x (29 - 28) = 23

a) -(2016 + 39 +17) - (39 - 17)

=  -2072 - 22

= -2094

b) 422 + (-85) + 278 -(-55)

=  337 + 278 -(-55)

=  615 -(-55)

=  670

c) 28 x (29-23) - 29 x (28 - 23)

=  28 x 6 - 29 x 6

= 168 - 174

= -6

mk nham phan a

a) -( 2016 + 39 + 17 )-(-39-17)

=  -2072 - (-56)

=  - 2016

`16/27xx13/29+16/27xx14/29`

`=16/27xx(13/29+14/29)`

`=16/27xx27/29`

`=16/29`

`48/49+15/39-18/49+15/39`

`=(48/49-18/49)+(15/39+15/39)`

`=30/49+30/39`

`=880/637`