1a, (-3,8) + [ (-5,7)+3,8]

= (-3,8+3,8) -5,7

= -5,7

b, 31,4 +[6,4 +(-18)]

= 31,4 - 11,6

= 19,8

c,[(9,6 )+4,5 ] +[9,6 +(-1,5)]

= 9,6 +9,6 +(4,5-1,5)

= 19,2 +3

=22,2

d, [ (-4,9) + (-7,8)] +[1,9+2,8]

= (-4,9 +1,9)+ (-7,8+2,8)

= -3 -5

=-8

e, (3,1-2,5)-(-2,5+3,1)

= (3,1-3,1)+(2,5-2,5)

=0

f, (5,3 -2,8 )- (4+5,3)

= (5,3-5,3) -2,8-4

= -6,8

g, -(251,3 +281 )+ 3,251 -(1-281)

= -251,3-281+3,251 -1+281

= (-281+281) -251,3 +3,251 -1

= -249,049

h,-(3/54+3/4)-(-3/4 +2/5)

= -3/54-3/4 +3/4 +2/5

=(-3/4+3/4) -3/54 +2/5

=123/270

chúc bạn học tốt

lấy mt bấm phắt là ra

A = (3,1 – 2,5)  – (-2,5 + 3,1) = 3,1 – 2,5 + 2,5 – 3,1 = 0

B  = (5,3 – 2,8) – (4 + 5,3) = 5,3 – 2,8 – 4 – 5,3

A=(3,1-2,5)-(-2,5+3,1)=3,1-2,5+2,5-3,1=0

B=(5,3-2,8)-(4+5,3)=5,3-2,8-4-5,3=-6,8

`@` `\text {Ans}`

`\downarrow`

`a,`

`A =(3,1 - 2,5) - (-2,5 + 3,1)`

`= 3,1 - 2,5 + 2,5 - 3,1`

`= (3,1 - 3,1) + (-2,5+2,5)`

`= 0`

Vậy, `A = 0`

`b,`

`B = (5,3 - 2,8) - (4+5,3)`

`= 5,3 - 2,8 - 4 - 5,3`

`= (5,3 - 5,3) + (-2,8-4)`

`= -6,8`

Vậy, `B = -6,8`

`c,`

`C = -(25 - 3 + 2,81) + 3,251 - (1 - 2,8)` `?`

`= -25 + 3 - 2,81 + 3,251 - 1 + 2,8`

`= (-25 + 3 - 1) + (-2,81 + 2,8) + 3,251`

`= -23 - 0,01 + 3,251`

`= -19,759`

a) \(A=\left(3,1-2,5\right)-\left(-2,5+3,1\right)\)

\(A=0,6-0,6\)

\(A=0\)

b) \(B=\left(5,3-2,8\right)-\left(4+5,3\right)\)

\(B=2,5-7,3\)

\(B=-6,8\)

c) \(C=-\left(25-3+2,81\right)+3,251-\left(1-2,8\right)\)

\(C=-24,81+3,251+1,8\)

\(C=-19,759\)

\(A=\left(3,1-2,5\right)-\left(-2,5+3,1\right)\)

\(=\left(3,1-2,5\right)-\left(3,1-2,5\right)\)

\(=3,1-2,5-3,1+2,5\)

\(=\left(3,1-3,1\right)+\left(2,5-2,5\right)\)

\(=0+0=0\)

\(B=\left(5,3-2,8\right)-\left(4+5,3\right)\)

\(=5,3-2,8-4-5,3\)

\(=\left(5,3-5,3\right)-\left(2,8+4\right)\)

\(=0-\left(2,8+4\right)\)

\(=-2,8-4=-6,8\)

\(A=\left(3,1-2,5\right)-\left(-2,5+3,1\right)\)

\(=3,1-2,5+2,5-3,1=0\)

\(B=\left(5,3-2,8\right)-\left(4+5,3\right)\)

\(=5,3-2,8-4-5,3=-6,8\)

\(C=-\left(251.3+281\right)+3.215-\left(1-281\right)\)

\(=-753-281+645-1+281\)

\(=-753+654-1=-100\)

\(D=-\left(\dfrac{3}{5}+\dfrac{3}{4}\right)-\left(\dfrac{-3}{4}+\dfrac{2}{5}\right)\)

\(=-\dfrac{3}{5}-\dfrac{3}{4}+\dfrac{3}{4}-\dfrac{2}{5}=\dfrac{-3}{5}-\dfrac{2}{5}=-1\)

\(A=\left(3,1-2,5\right)-\left(-2,5+3,1\right)\)

\(=3,1-2,5+2,5-3,1\)

\(=\left(3,1-3,1\right)-\left(2,5-2,5\right)\)

\(=0\)

Vậy \(A=0.\)

\(B=\left(5,3-2,8\right)-\left(4+5,3\right)\)

\(=5,3-2,8-4-5,3\)

\(=\left(5,3-5,3\right)-\left(2,8+4\right)\)

\(=-\dfrac{34}{5}\)

Vậy \(B=\dfrac{-34}{5}.\)

\(C=-\left(251.3+281\right)+3.215-\left(1-281\right)\)

\(=-251.3-281+3.215-1+281\)

\(=-753-\left(281-281\right)+645\)

\(=-753+645=-108\)

Vậy \(C=-108.\)

\(D=-\left(\dfrac{3}{5}+\dfrac{3}{4}\right)-\left(-\dfrac{3}{4}+\dfrac{2}{5}\right)\)

\(=-\dfrac{3}{5}-\dfrac{3}{4}+\dfrac{3}{4}-\dfrac{2}{5}\)

\(=\left(\dfrac{-3}{5}-\dfrac{2}{5}\right)-\left(\dfrac{3}{4}-\dfrac{3}{4}\right)\)

\(=-1\)

Vậy D = -1.

A=(3,1-2,5)-(-2,5+3,1)
A=3,1-2,5=2,5-3,1

A=(3,1-3,1)+(2,5-2,50

A=0

B=(5,3-2,8)-(4+5,3)

B=5,3-2,8-4-5,3

B=(5,3-5,3)-(4+2,8)

B=0-6,8

B=-6,8

C=-(251.3+281)+3.215-(1-281)

C=-251.3-281+3.215-1+281

C=3(-251+215)-(281+281)-1

C=-108-1

C=-109
D=\(-\left(\dfrac{3}{5}+\dfrac{3}{4}\right)-\left(-\dfrac{3}{4}\right)+\dfrac{2}{5}\)
\(D=-\dfrac{3}{5}+-\dfrac{3}{4}+\dfrac{3}{4}+\dfrac{2}{5}\)

D=\(\left(-\dfrac{3}{5}+\dfrac{2}{5}\right)+\left(-\dfrac{3}{4}+\dfrac{3}{4}\right)\)

\(D=\dfrac{-1}{5}\)

bai 4:

A=1,711

B,=-2,2229

C,=-4,157

D,=-9,74

E,=10

F,=-70

G,=1

nhieu vai

Bài 5 :

a, ( -4,8 ) + \(\left[\left(-5,7\right)+\left(4,8\right)\right]\)

= (-4,8) + ( 4,8 ) + ( -5,7 )

= (-5,7 )

b) [(-9,6) + (+1,5)] + [(+9,6) + (-1,5)]

= (-9,6 ) + 9,6 + 1,5 + ( -1,5 )

= 0

c) (3,1 - 2,5) - (-2,5 + 3,1)

= 3,1 - 2,5 + 2,5 - 3,1

= 3,1 -3,1 -2,5 + 2,5

=0

= 3,1 - 2,5 + 2,5 + 3,1

= ( 3,1 - 3,1 ) + ( -2,5 - 2,5 )

= 0

d) 2,7 - (-4,3) + (-8,5) - (-0,6)

= 2,7 + 4,3 - 7 ,9

= 7 - 7,9

= -0,9

d) 2,7 - (-4,3) + (-8,5) - (-0,6)

= 2,7 + 4,3 + 8,5 + 0,6

= 7 + 9,1

= 16,1

e, - \(\left(\dfrac{3}{5}+\dfrac{3}{4}\right)-\left(\dfrac{3}{4}+\dfrac{2}{5}\right)\)

= \(\dfrac{-3}{5}+\dfrac{3}{4}-\dfrac{3}{4}-\dfrac{2}{5}\)

= \(\dfrac{-3}{5}-\dfrac{2}{5}+\dfrac{3}{4}-\dfrac{3}{4}\)

= -1

f) [(-4,9) + (-37,8)] + [(+1,9) + (+2,8)]

= - 4,9 - 37,8 + 1,9 + 2,8

= ( -4,9 + 1,9 ) + ( -37,8 + 2,8 )

= -3 + (-35)

= -38

g) (-4,1) + (-13,7) + (+31) + (-5,9) + (-6,3)

= (-4,1) + ( -5,9 ) + ( -13,7 ) + ( -6,3) + 31

= - 10 - 20 + 31

= 1

h) (-6,5) . 2,8 + 2,8 . (-3,5)

= 2,8 . [ -6,5 - 3,5 ]

= 2,8 . (-10 )

= - 28

a) (-35,8) + (-17,2) + 16,4 + 4,6

= [ (-35,8) + (-17,2) ] + (16,4 + 4,6)

= -53 + 21

= -32

b) (5,3 - 2,8) - (4 + 5,3)

= 2,5 - 9,3

= -6,8

c) (34,72 + 32,28):5 - (57,25 - 36,05):2

= 67:5 - 21,2:2

= 13,4 - 10,6

= 2,8

d) 2,5.(-4,68) + 2,5.(-5,32)

= 2,5.[ (-4,68) + (-5,32) ]

= 2,5. (-10)

= -25

e) 5,36. 12,34 + (-5,36). 2,34

= 5,36. 12,34 - 5,36. 2,34

= 5,36. (12,34 - 2,34)

= 5,36. 10

= 53,6

a,-35,8+(-17,2)+16,4+4,6=(-35,8-17,2)+(16,4+4,6=-53+21=-32

b,(5,3-2,8)-(4+5,3)=5,3-2,8-4-5,3=(5,3-5,3)+(-2,8-4)=0-6,8=-6,8.

c,(34,72+32,28):5-(57,25-36,05):2=67:5-21,2:2=13.4-10.6=2,8

d,2,5(-4,68)+2,5(-5,32)=2,5(-4,68-5,32)=2,5x(-10)=-25

e,5,36x12,34+(-5,36)x2,34=5,36(12,34-2,34)=5,36x10=53,6