\(a,1.2155-\left(174+2155\right)+\left(-68+174\right)\)

\(=2155-2155-174+174-68\)

\(=-68\)

\(b,-25.72+25.21-49.25\)

\(=25\left(-72+25-49\right)\)

\(=25.\left(-96\right)\)

\(=-2400\)

1. a, 15-(3+x)+2x=19
=> 15- 3 - x + 2x = 19
=> -x + 2x = 19 - 15 +3
=> ( -1 + 2 )x = 7
=> x = 7
b, (-58)-(19-58-x)=60
=> (-58)-(-39-x)=60
=> -58 +39 + x = 60
=> -19 + x = 60
=> x = 60 - (-19) = 79
c, 2(x-4)-3(x+5)=4
=> (2x - 8 )-(3x+15)= 4
=> 2x - 8 - 3x - 15 = 4
=> 2x - 3x = 4 + 15 + 8
=> - x = 27
=> x = -27
d, (2-3x)+(x-3)=(5x-1)-(5x-2)
=> 2 - 3x + x - 3 = 5x - 1 - 5x + 2
=> 2 - 3 - 3x + x = 5x - 5x - 1 +2
=> 2 - 3 - 3x + x = 1
=> - 3x + x = 1 - 2 + 3
=> -2x = 2
=> x= -1
=))))

2.

a,

A= -3752-(29-3632)-51

A= -3572-29+3632-51

A=(-3572+3632)-29-51

A=

Đáp án đúng là :C. 3 025 674

1. -25.72 + 25.21 - 49.25

= 25.(-72) + 25.21 - 49.25

= 25.(-72 + 21 - 49)

= 25. (-100)

= -2500

2. 35(14 - 23) - 23(14 - 35)

= 35. (-9) - 23. (-9)

= -9(35 - 23)

= -9. 12

= -108

3. 8154 -(674 + 8154) + (-98 + 674)

= 8154 - 674 - 8154 + (-98) + 674

= 8154 - 8154 - 674 + 674 + (-98)

= -98

4. 25.21 + 25.72 + 49.25

= 25(21 + 72 + 49)

= 25. 142

= 3550

5. 27(13 - 16) - 16(13 - 27)

= (27.13 - 27.16) - (16.13 - 16.27)

= 27.13 - 27.16 - 16.13 - 16.27

= 27.13 - 16.13 - 27.16 - 16.27

= 27.13 - 16.13

= 13(27 - 16)

= 13.11

= 143

6. -1911 -(1234 - 1911)

= -1911 - 1234 + 1911

= -1911 + 1911 - 1234

= -1234

35.(14-23)-23.(14-35)

=35.14-35.23-23.14+23.35

=-35.23+23.35+35.14-23.14

=0+14.(35-23)

=14.12

=168

8154-(674+8154)+(-98+674)

=8154-674-8154-98+674

=8154-8154-674+674-98

=-98

/x-3/-7=13

/x-3/=13+7

/x-3/=20

x-3=20 hay x-3 =-20

x=23 hay x=-17

-12.(x-5)+7.(3-x)=5

-12.x+60+21-7x=5

-19x=-76

x=4

a: =674x100=67400

674 x 99 + 674                             978 x 101 - 978

= 674 x ( 99 + 1 )                          = 978 x ( 101 - 1 )

= 674 x 100                                   = 978 x 100

= 67400                                         = 97800

bằng 71984088

:D

1000-5+674

=995+674

=1669

ban tra loi di roi minh tk cho

tk nhe@@@@@@@@@!!!$

1000-5+674

=995+674

=1669

tk nhé truong thi cam vy

1: Ta có: \(2155-\left(174+2155\right)+\left(-68+174\right)\)

\(=2155-174-2155-68+174\)

=-68

2) Ta có: \(-25\cdot72+25\cdot21-49\cdot25\)

\(=-25\cdot\left(72-21+49\right)\)

\(=-25\cdot100=-2500\)

a) 8154- (674+8154)+(-98+674)

= 8154- 674- 8154+ 98+ 674

= (8154- 8154)+(-674+ 674)+98

= 0+0+98

=98

b)32.(-39)+16.(-220)

= -1248+(-3520)

= -4768

:))