\(a,123\times54+27\times123-12\times123+123\times31\)

\(=123\times\left(54+27-12+31\right)\)

\(=123\times100\)

\(=12300\)

\(b,\dfrac{121}{27}\times\dfrac{54}{11}< n< \dfrac{100}{21}:\dfrac{25}{126}\)

\(22< n< \dfrac{100}{21}\times\dfrac{126}{25}\)

\(22< n< 24\)

Vì \(23>22\) và \(23< 24\) nên \(n=23\)

a, 123x(54+27-12+31)

=123x100

=12300

a123x54+27x123-12x123+123x31

=123:54+27:123-12:123+123:31

=6642+27:123-12:123+123:31

=6642+3321-12:123+123:31

=6642+3321-1476+123:31

=6642+3321-1476+3813

=12300

b,121/27x54/11<n>100/21:25/126

=22<n>24

n=23

Bỏ dấu ngoặc rồi tính:

a) (123 - 27)+ (27+ 13-123) -= 123 - 27 + 27 + 13 - 123 = 13

​​b) (175 + 25 + 13)-(-15 + 175 + 25) = 175 + 25 + 13 + 15 - 175 - 25 = 28

c) (2012 - 119 + 29) - (-119 + 29) = 2012 - 119 + 29 + 119 - 29 = 20122

​​d) -(55 - 80 + 91) - (2012 + 80 - 91) = - 55 + 80 - 91 - 2012 - 80 + 91 = - 2067

e) 123 + [54 + (-123) + 46] = 123 + 54 - 123 + 46 = 100

f) - 64 + [(-110 + 64 + 71] = -64 -110 +64 + 71 = -39

a) \(5\times x-123=12\)

\(\Rightarrow5\times x=135\)

\(\Rightarrow x=27\)

b) \(x+3x+5x+7x=96\)

\(\Rightarrow16x=96\)

\(\Rightarrow x=6\)

a) \(5\times x-123=12\)

\(5x=12+123\)

\(5x=135\)

\(x=135:5\)

\(x=27\)

________

b) \(x+3x+5x+7x=96\)

\(x\left(1+3+5+7\right)=96\)

\(x.16=96\)

\(x=96:16\)

\(x=6\)

a)

\(5\times x-123=12\\\Rightarrow 5\times x=12+123\\\Rightarrow 5\times x=135\\\Rightarrow x=135:5\\\Rightarrow x=27\\---\)

b) 

\(x+3x+5x+7x=96\\\Rightarrow16x=96\\\Rightarrow x=96:16\\\Rightarrow x=6\)

a) ( 123-27) +( 27+13-123)

= 123-27+27+27+13-123

= 123+13-123

= 13

b) (2020 -119 + 29) -(-119+29)

=2020-119+29+119-29

=2020+(119-119)+(29-29)

=2020

a) (123 - 27) +(27 + 13 - 123 )

= 123 - 27 +27 + 13 - 123 

= 123- 123 -27 +27 +13

= 13

b)( 2020 - 119 +29 ) - (-119 +29 )

=2020 - 119 + 29 + 119 -29

= 2020 -119 + 119 + 29 - 29

=2020

a) (123 - 27) +(27 + 13 - 123 )

= 123 - 27 +27 + 13 - 123 ( bỏ ngoặc )

= 123- 123 -27 +27 +13

= 0-0+13=13

b)( 2020 - 119 +29 ) - (-119 +29 )

=2020 - 119 + 29 + 119 -29( bỏ ngoặc )

= 2020 -119 + 119 + 29 - 29

=2020 -0+0=2020

96.(-27)+27. (-104)

= -96.27+27.(-104)

= 27 [  -96 + ( -104) ]

= 27. (-200)

= - 5400

c: =53*55+53*145+53

=53*201

=10653

d: Số số hạng là (126-3):3+1=42(số)

Tổng là (126+3)*42/2=2709

c: =2012-119+29+119-29

=2012

Bấm máy tính ta đc kết quả là: \(-530\)

\(\text{-457+(-123)+23+27}\)

\(\text{= -457-123+23+27}\)

\(\text{= (-457+27) - (123-23)}\)

\(\text{= -430 - 100 = -530}\)