a) -158 - (532 - 158) + 32
= -158 - 374 + 32
= -532 + 32
=-500

b) (34-419)-(34-76-419)
=- 385 -(-42-419)
=-358-(-461)
=103

a/-158-374+32

=-532+32=-500

 b/-385--461=76

a: \(72\cdot56+56\cdot28=56\left(72+28\right)=5600\)

b: \(53\cdot125-24\cdot53-53=53\left(125-24-1\right)=5300\)

c: \(42\cdot53+47\cdot156-47\cdot114=42\cdot53+47\cdot42=4200\)

d: \(28\cdot76+28\cdot25+28=28\cdot\left(76+25+1\right)=2800\)

e: \(37\cdot59-37\cdot3+37\cdot49=37\left(59-3+49\right)=3885\)

a) \(72.56+56.28=56\left(72+28\right)=56.100=5600\)

b) \(53.125-24.53-53=53\left(125-25-1\right)=53.100=5300\)

c) \(42.53+47.156-47.114=42.53+47\left(156-114\right)=42.53+47.42=42\left(53+47\right)=42.100=4200\)

d) \(28.76+28.25+28=28\left(76+25+1\right)=28.102=2856\)

e) \(37.59-37.3+49.37=37\left(59-3+49\right)=37.105=3885\)

f) \(2.14.18+3.12.17+4.69.9=36\left(14+17+69\right)=36.100=3600\)

a) = 56 . ( 72 + 28 )

 = 56 . 100

= 5600

b) = 53 . ( 125 - 24 - 1 )

= 53 . 100

= 5300

c) = 42 . 56 + 47 . ( 156 - 114 )

= 42 . 56 + 47 . 142

= 2352 + 6674

= ... 

d)= 28 . ( 76 +  25 +1 ) 

= 28 . 102

=...

e) = 37 . ( 59 - 3 + 49 )

= 37 . 13

=...

a) 3 x 5² + 15 x 2² - 26 : 2

= 3 x 25 + 15 x 4 - 13

= 75 + 60 - 13

= 135 - 13

= 122

b) 5³ x 2 - 100 : 4 + 2³ x 3

= 125 x 2 - 25 + 8 x 3

= 250 - 25 + 24

= 225 + 24

= 249

c) 3² : 5 + 2³ x 10 - 81 : 3

9 : 5 + 8 x 10 - 27

= 1,8 + 80 - 27

= 81,8 - 27

= 54,8

a, \(3\left(2x+1\right)^2-2\left(x-5\right)^2+\left(x-1\right)\left(x+2\right)\)

\(=3\left(4x^2+4x+1\right)-2\left(x^2-10x+25\right)+x^2+x-2\)

\(=12x^2+12x+3-2x^2+20x-50+x^2+x-2\)

\(=11x^2+33x-49\)

\(3\left(2x+1\right)^2-2\left(x-5\right)^2+\left(x-1\right)\left(x+2\right)\)

\(=3\left(4x^2+4x+1\right)-2\left(x^2-10x+10\right)+x^2+2x-x-2\)

\(=12x^2+12x+3-2x^2-20x-20+x^2+2x-x-2\)

\(=11x^2+33x-15\)

Trả lời:

3 ( 2x + 1 )² - 2 ( x - 5 )² + ( x - 1 )( x + 2 )

= 3 ( 4x² + 4x + 1 ) - 2 ( x² - 10x + 25 ) + x² + x - 2 

= 12x² + 12x + 3 - 2x² + 20x - 50 + x² + x - 2 

= 11x² + 33x - 49

A)25%-1 1/3+0,5.12/5 =1/4-4/3+1/2.12/5=3/12-16/12+6/5=-13/12+6/5=7/60                                                                                                             8x=7,8.x+25.    8x-7,8x=25.     0,2x=25.       x=25:0,2.        x=125

a) 215+(-38)-(-58)+9-85

=215-38+58+9-85

=(215-38)+(58+9)-85

=177+67-85

=159

b)(1267-196)-(267-304)

=1071-(-37)

=1108

c)(3965-2378)-(437-1378)-528

=1578-(-941)-528

=2000.

Con d mk chiu.

a) 215 + (-38) - (-58) + 9-85

=215 - 38 + 58 + 9 - 85

=(215 - 38) + (58 + 9) - 85

=177 + 67 - 85

=159

b)(1267 - 196) - (267 - 304)

=1071 - (-37)

=1108

c)(3965 - 2378) - (437 - 1378) - 528

=1578 - (-941) - 528

=2000

*Lười quá nên ko ghi lại đề nhé!!*

B1:

=-9

=-24

B2:

a,

= 5.(-50) = -250

b, 

= 6.(-40) = -240

cứu với huhuhuhuhuhuhuhuhuhhuhu

giúp mình đi mà !!! mình xin đấy!!!!!!!!!!!!!!☺❤

Bài 1:

\(\frac{1}{2}.\frac{1}{3}+\frac{1}{3}.\frac{1}{4}+....+\frac{1}{8}.\frac{1}{9}\)

\(=\frac{1}{2.3}+\frac{1}{3.4}+....+\frac{1}{8.9}\)

\(=\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+.....+\frac{1}{8}-\frac{1}{9}\)

\(=\frac{1}{2}-\frac{1}{9}=\frac{7}{18}\)

\(1+\frac{1}{3}+\frac{1}{6}+\frac{1}{10}+...+\frac{1}{x\left(x+1\right):2}=1\frac{2016}{2017}\)

\(\Rightarrow\frac{1}{2}\left(1+\frac{1}{3}+\frac{1}{6}+\frac{1}{10}+...+\frac{2}{x\left(x+1\right)}\right)=\frac{1}{2}.\frac{4033}{2017}\)

\(\Leftrightarrow\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{x\left(x+1\right)}=\frac{4033}{4034}\)

\(\Rightarrow\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+...+\frac{1}{x\left(x+1\right)}=\frac{4033}{4034}\)

\(\Rightarrow1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{x}-\frac{1}{x+1}=\frac{4033}{4034}\)

\(\Rightarrow1-\frac{1}{x+1}=\frac{4033}{4034}\)

\(\Rightarrow\frac{1}{x+1}=1-\frac{4033}{4034}\)

\(\Rightarrow\frac{1}{x+1}=\frac{1}{4034}\)

\(\Rightarrow x+1=4034\)

\(\Rightarrow x=4034-1\)

\(\Rightarrow x=4033\)

từ tính đê lười thế