b/ (-127).57+(-127).43

=(-127)(57+43)

=(-127).10

=-1270

c/ (-13).34-87.34

=34.(-13-87)

=34.(-100)

=3400

a) (-14).(-125).(+3).(-8)

= [(-14).3].[(-125).(-8)]

=     -42  . 1000

=        -42000

b) (-127).57+(-127).43

= -127.(57+43)

= -127.100

=    -12700

c) (-13).34-87.34

= 34.(-13-87)

= 34.(-100)

=  -3400

d) (-25).68+(-34).(-250)

=  - 1700 + 8500

=         6800        ( bài này không cần phải tính hợp lý )

tick nha các bạn yêu quý

sdsds

\(B=\left(-25\right)\times68+\left(-34\right)\cdot\left(-250\right)\)

\(\Rightarrow B=-25\times68-34\times\left(-25\right)\times10\)

\(\Rightarrow B=\left(-25\right)\times\left(68-340\right)\)

\(\Rightarrow B=\left(-25\right)\times\left(-272\right)\)

\(\Rightarrow B=6800\)

B = (-25)68 + (-34)(-250)

    = -25.34.2 - 34(-250)

    = 34(-50 + 250)

    = 34.200

    = 6800

B = (-25).68+(-34).(-250)

B = (-25).(-34).(-2)+(-34).(-25).10

B = ( -25 ).(-34) .[ (-2) + .10 ]

B = (-25).(-34). 8

B = ( -25 ).4.(-34).2

B = -100.(-68)

B = -6800

giúp ik >< 

( -25) x 68 + ( - 34 ) x ( - 250 )

= ( -25 ) x 34 x 2 + ( - 34 ) x ( - 250)

= 25 x 2 x ( - 34 ) + ( - 34 ) x ( - 250 )

= 50 x ( - 34 ) + ( - 34 ) x ( - 250 )

= ( -  34 ) x [ 50 + ( -250 )

= ( - 34) x ( - 200 )

= ( - 34 ) x 2 x ( -100 )

 = 3400 x 2 

=6800

(-25).68+34.(250)

=25.68+34.250

=25.68+34.25.10

=25.(68+34).10

=25.100.10=2500

(-25) . 68 + ( -34) . (-250)

= ( -25) .68 + (-34) . 10 . (-25)

=(-25)  .68 + ( -340 ) .(-25)

= (-25) . ( 68-340)

= (-25). ( -272)

=6800

(-25). 68 + (-34). (-250)

=(-25).(34.2)+(34.2).(25.5)

=68.(-25)+68.(25.5)

= 68[25+25.(-5)]

= 68{25[1+(-5)]}

= 68 (25.4)

=68. 100= 6800

mk làm đúng 100% đó mk tính đi tính lại r nên bn cứ yên tâm (ko sai dù chỉ 1 dấu -)

a: \(=\dfrac{48-45}{54}\cdot\dfrac{9}{4}=\dfrac{3}{54}\cdot\dfrac{9}{4}=\dfrac{27}{216}=\dfrac{1}{8}\)

b: \(=\dfrac{6}{5}+1=\dfrac{11}{5}\)

c: \(=\dfrac{7\cdot28\cdot15}{9\cdot25\cdot14}=\dfrac{1}{2}\cdot\dfrac{28}{25}\cdot\dfrac{5}{3}=\dfrac{140}{150}=\dfrac{14}{15}\)

3,2 + 4,65 : 1,5 

=3,2+3,1

=6,3

347 + 418 + 123 + 12

=(347+123)+(418+12)

=470+430

=900

34 x 35 + 35 x 38 + 65 x 40 + 65 x 32

=35*(34+38)+65*(32+40)

=35*72+65*72

=72*(35+65)

=72*100

=7200

19 x 16 x 4 + 76 x 34

=76*16+76*34

=76*(16+34)

=76*50

=3800

136 x 68 + 16 x2 x 136 

=136*68+32*136

=136*(68+32)

=136*100

=13600

125 x 25 + 125 x 74 + 125

=125*(25+74+1)

=125*100

=12500

Tính bằng cách thuận tiện hả

3,2 + 4,65 : 1,5 = 3,2 + 3,1 = 6,3

347 + 418 + 123 + 12 = (347 + 123) + (418 + 12) = 470 + 430 = 900

34 x 35 + 35 x 38 + 65 x 40 + 65 x 32 = 35 x ( 34 + 38) + 65 x (40 + 32) = 35 x 72 + 65 x 72 = 72 x (35 + 65) = 72 x 100 = 7200

19 x 16 x 4 + 76 x 34

136 x 68 + 16 x2 x 136 

125 x 25 + 125 x 74 + 125

Câu 5:

a: \(31\cdot\left(-18\right)+31\cdot\left(-81\right)-31\)

\(=31\left(-18-81-1\right)\)

\(=31\cdot\left(-100\right)=-3100\)

b: \(\left(-12\right)\cdot47+\left(-12\right)\cdot52+\left(-12\right)\)

\(=\left(-12\right)\left(47+52+1\right)\)

\(=-12\cdot100=-1200\)

c: \(13\cdot\left(23+22\right)-3\cdot\left(17+28\right)\)

\(=13\cdot45-3\cdot45\)

\(=45\cdot10=450\)

d: \(-48+48\left(-78\right)+48\left(-21\right)\)

\(=48\left(-1-78-21\right)\)

\(=48\left(-100\right)=-4800\)

Câu 4:

a: \(\left(-6-2\right)\left(-6+2\right)=\left(-8\right)\cdot\left(-4\right)=32\)

b: \(\dfrac{\left(7\cdot3-3\right)}{-6}=\dfrac{21-3}{-6}=\dfrac{18}{-6}=-3\)

c: \(\left(-5+9\right)\cdot\left(-4\right)=4\cdot\left(-4\right)=-16\)

d: \(\dfrac{72}{-6\cdot2+4}=\dfrac{72}{-12+4}=\dfrac{72}{-8}=-9\)