(-53).21 = (-53).(20 + 1) = (-53).20 + (-53).1 = -1060 + (-53) = -1113

a)  − 53.21 = − 53. ( 20 + 1 ) = − 53.20 + ( − 53 ) .1 = − 1060 + − 53 = − 1103

b)    45. ( − 12 ) = 45. − 10 − 2 = 45. − 10 − 45.2 = − 450 − 90 = − 540.

c)  102. ( − 25 ) = 100 + 2 . − 25 = 100. − 25 + 2. − 25 = − 2500 − 50 = − 2550

d)    − 63.41 = − 63. 40 + 1 = − 63.40 + − 63 .1 = − 2520 − 63 = − 2583

  45. ( − 12 ) = 45. − 10 − 2 = 45. − 10 − 45.2 = − 450 − 90 = − 540.

45.(-12) = 45.[(-10) + (-2)] = 45.(-10) + 45.(-2) = -450 + (-90) = -540

a)\(\left(-57\right).11\)

\(=\left(-57\right)\left(10+1\right)\)

\(=\left(-57\right).10+\left(-57\right).1\)

\(=\left(-570\right)+\left(-57\right)\)

\(=-\left(570+57\right)\)

\(=-627\)

b) \(75.\left(-21\right)\)

\(=75.\left(-20-1\right)\)

\(=75\left(-20\right)-75.1\)

\(=-1500-75\)

\(=-1575\)

a) -57.11=-57.(10+1)=-570-57=-627

b) 75.(-21)=-75.21=-75.(20+1)=-1500-75=-1575

k nhé mn!

a)-57.11=-57.(10+1)=-57.10+(-57).1=-570+(-57)=-627

b)75.(-21)=75.((-20)+(-1))=75.(-20)+75.(-1)=-1500-75=-1575

mk chỉ lm dc vậy, có thể có cách khác, mk góp í cách này

a) -53 . 21

= -53 . (10 + 11)

= (-53 . 10) + (-53 . 11)

= -530 + (-583)

= -1113

a) -53 . 21

= -53 .( 10 + 11)

= -53 .10 + (-53) .11 = - 530 + ( -583) = -1113

b) 45. (-12)

= 45 . [ -10+ (-2)]

= 45. (-10) + 45 . (-2)

= -450 + ( -90)

= -540

a)(-53).21=(-53).(20+1)=(-1060)+(-53)=-1113

b)45.(-12)=45.[(-10)+(-2)]=(-450)+(-90)=-540