Giúp em với ạ thanks a.[3.(x+2):7].4=120 b.x.(x-1)=0 c.(2+x).(x-4)=0 d.(x-140):7=3³-2³.3

2 bình luận về “Giúp em với ạ thanks a.[3.(x+2):7].4=120 b.x.(x-1)=0 c.(2+x).(x-4)=0 d.(x-140):7=3³-2³.3”

1. a)

   [3.(x+2):7].4=120

   =>3.(x+2):7=120:4

   =>3.(x+2):7=30

   =>(x+2):7=30:3

   =>(x+2):7=10

   =>x+2=10.7

   =>x+2=70

   =>x=68

   Vậy x=68

   b)

   x.(x-1)=0

   =>[(x=0),(x-1=0):}

   =>[(x=0),(x=1):}

   Vậy x in {0;1}

   c)

   (2+x).(x-4)=0

   =>[(2+x=0),(x-4=0):}

   =>[(x=-2),(x=4):}

   Vậy x in {-2;4}

   d)

   (x-140):7=3^3-2^(3).3

   =>(x-140):7=27-8.3

   =>(x-140):7=27-24

   =>(x-140):7=3

   =>x-140=3.7

   =>x-140=21

   =>x=161

   Vậy x=161

    

   Trả lời
2. Giải đáp:

   a)

   [3.(x+2):7].4=120

   => 3.(x+2):7=120:4

   => 3.(x+2):7=30

   => 3.(x+2)=30.7

   => 3.(x+2)=210

   => x+2=210:3

   => x+2=70

   => x=70-2

   => x=68

   Vậy x=68

   b)

   x.(x-1)=0

   Ta xét 2TH:

   +)TH1:x=0

   +)TH2: x-1=0

   =>x=1

   Vậy x\in{0;1}

   c)

   (2+x).(x-4)=0

   Ta xét 2TH:

   +)TH1: 2+x=0

   => x=0-2

   => x=-2

   +)TH2: x-4=0

   => x=0+4

   => x=4

   Vậy x\in{-2;4}

   d)

   (x-140):7=3^{3}-2^{3}.3

   =>(x-140):7=3.(3^{2}-2^{3})

   => (x-140):7=3.(9-8)

   => (x-140):7=3.1

   => (x-140):7=3

   => x-140=3.7

   => x-140=21

   => x=21+140

   => x=161

   Vậy x=161

   Trả lời