=81:9x8

=9x8=72

=9² : 9 . 8 + 1
=9 . 8 + 1 = 73

0

6456 x 0=0

0

\(=921-921\times\dfrac{1}{38}\)

\(=921\times\left(1-\dfrac{1}{38}\right)=921\times\dfrac{37}{38}=\dfrac{34077}{38}\)

921 - 921 : 38

= 921 x 1 - 921 x 1/38

= 921 x ( 1 - 1/38)

= 921 x  37/38

= 34077/38

921 - 921 : 38

= 921 x 1 - 921 x 1/38

= 921 x ( 1 - 1/38)

= 921 x  37/38

= 34077/38

a, 921 + [ 97 + (-921) + ( -47)]

= 921 + 97 - 921 - 47

= (921 - 921) + (97 - 47)

= 50

b, 2013 + 2014 + 2015+ 2016 + ( -2017) + (-2018) + (-2019) + (-2020)

= 2013 + 2014 + 2015 + 2016 - 2017 - 2018 - 2019 - 2020

= (2013 - 2017) + (2014 - 2018) + (2015 - 2019) + (2016 - 2020)

= -4 - 4 - 4 - 4

= -16

Bài làm

a) 921 + [ 97 + (-921) + ( -47) ]

= 921 + 97 + ( -921 ) + ( -47 )

= [ 921 + ( -921 ) ] + [ 97 + ( -47 ) ]

= 0 + 50

= 50

b) 2013 + 2014 + 2015+ 2016 + ( -2017) + (-2018) + (-2019) + (-2020)

= [ 2013 + ( -2017 ) ] + [ 2014 + ( -2018 ) ] + [ 2015 + ( -2019 ) ] + [ 2016 + ( -2020 ) ]

=           -4                  +             ( -4 )           +            ( -4 )            +             ( -4 )

= -16

# Chúc bạn học tốt #

\(44.179+20^2-79.44\\ =44\left(179-79\right)+400\\ =44.100+400\\ =100\left(44+4\right)=4800\\ 3.4^2:\left[500-\left(7.35+125\right)\right]\\ =3.16:\left[500-370\right]\\ =48:130=\dfrac{24}{65}\\ 187+\left[921-\left(921+887\right)\right]\\ =187+921-921-887\\ =187-887=-700\)

44. 179+ 20² - 79.44 3. 4² : [500- (7.35+125)]

= 44. 179+400 - 79.44 = 3. 16: [500- (245+125)]

= 44. (179-79) +400 = 48: [ 500-370 ]

= 44. 100+400 = 48:130

= 4400+400 = 0, 369...

= 4800

187+ [ 921-( 921+887) = 187+ [921- 1808]

= 187+ (-159)

= 28

\(a)44.179+20^2-79.44\)

\(=44.\left(179-79\right)+20^2\)

\(=44.100+400\)

\(=4400+400=4800\)

\(b)3.4^2:\left[500-\left(7.35+125\right)\right]\)

\(=3.4^2:\left[500-\left(245+125\right)\right]\)

\(=3.4^2:\left[500-370\right]\)

\(=3.16:130\)

\(=48:130=\dfrac{24}{65}\)

\(c)187+\left[921-\left(921+887\right)\right]\)

\(=187+\left[921-1808\right]\)

\(=187+\left[921-1808\right]\)

\(=187+\left(-887\right)\)

\(=-700\)

a ) 4 7 + 1 7 + 3 7 = 8 7 b ) 4 7 + − 3 7 + − 1 2 + 1 2 = 1 7

c ) − 27 10 + − 3 10 + 1 4 + 5 4 + 13 2 = − 3 + 3 2 + 13 2 = 5 d ) 8 5 + 7 5 + − 11 4 + − 9 4 + − 7 20 = 3 − 5 + − 7 20 = − 47 20 e ) 7 5 + − 1 15 + − 11 3 + 11 2 + 1 6 + ( − 2 ) = 4 3 + 2 + ( − 2 ) = 4 3

921+125= 1046

1046 k mk k lại

921+125=1046 nhé

999 – x = 999 – 921

999 – x = 78

x = 999 – 78

x = 921

x + 850 = 921 + 79

x + 850 = 1000

         x = 1000 - 850

         x = 150

x + 850 = 921 + 79

x + 850 = 1000

x           = 1000 - 850

x           = 150

tk mk mk tk lai

x+850=921+79

x+850=1000

x       = 1000-850

x       =150

bạn tk mk, mk tk lại.