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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 7: 6. . Tính: a) 1, (2) + 2, (3) b) 2, 2(12) + 4,(14) c) 5, 12(123) – 2, 11(101) c) 2,(3) . 3,(2)+ 2,(3). 5,(8)

Tháng Tám 6, 2022 Toán học 2 Comments 0 views

Toán Lớp 7: 6. . Tính:
a) 1, (2) + 2, (3)
b) 2, 2(12) + 4,(14)
c) 5, 12(123) – 2, 11(101)
c) 2,(3) . 3,(2)+ 2,(3). 5,(8)

Comments ( 2 )

  1. phuongthuydung
    phuongthuydung
    6 Tháng Tám, 2022 at 3:14 sáng
    Reply
    a) 1,(2) + 2,(3) = 3,(5)
    b) 2,2(12) + 4,(14)
    = 6,3(53)
    c) 5,12(123) – 2,11(101)
    = 3,1(22)
    d) 2,(3) . 3,(2)  +2,(3). 5,(8)
    = 2,(3).( 3,(2) + 5,(8))
    = 2,(3) . 9
    = 21

  2. daolanhoa
    daolanhoa
    6 Tháng Tám, 2022 at 3:14 sáng
    Reply
    Giải đáp:
    Bạn tham khảo đáp án bên dưới nhé!
    Lời giải và giải thích chi tiết:
    a)
    $1,2=1,2222…\\A=1,2222…\\\Rightarrow 10A=12,2222…\\\Rightarrow 10A-A=12,2222…-1,2222…\\\Rightarrow 9A=11\\\Rightarrow A=\dfrac{11}{9}\\2,3=2,3333…\\\Rightarrow A’=2,3333…\\\Rightarrow 10A’=23,3333…\\\Rightarrow 10A’-A’=23,3333…-2,3333…\\\Rightarrow 9A’=21\\\Rightarrow A’=\dfrac{21}{9}\\\Rightarrow 1,(2)+2,(3)\\=\dfrac{11}{9}+\dfrac{21}{9}\\=\dfrac{32}{9}$
    b) 
    $2,2(12)=2,212121…\\\Rightarrow A=2,212121…\\\Rightarrow 100A=221,21212…\\\Rightarrow 100A-A=221,21212…-2,212121…\\\Rightarrow 99A=219\\\Rightarrow A=\dfrac{219}{99}\\4,(14)=4,141414…\\\Rightarrow A’=4,141414…\\\Rightarrow 100A’=414,141414…\\\Rightarrow 100A’-A’=414,141414…-4,141414…\\\Rightarrow 99A’=410\\\Rightarrow A’=\dfrac{410}{99}\\\Rightarrow 2,2(12)+4,(14)\\=\dfrac{219}{99}+\dfrac{410}{99}\\=\dfrac{629}{99}$
    c)
    $5,12(123)=5,12123123…\\\Rightarrow A=5,12123123…\\\Rightarrow 100\ 000A=512123,123123…\\\Rightarrow 100A=512,123123…\\\Rightarrow 100\ 000A-100A=512123,123123-512,123123\\\Rightarrow 99\ 900A=511\ 611\\\Rightarrow A=\dfrac{170\ 537}{33\ 300}\\2,11(101)=2,11101101…\\\Rightarrow A’=2,11101101…\\\Rightarrow 100\ 000A’=211101,101101…\\\Rightarrow100A’=211,101101…\\\Rightarrow 100\ 000A’-100A’=211\ 101,101101-211,101101\\\Rightarrow 99\ 900A’=210\ 890\\\Rightarrow A’=\dfrac{21089}{9\ 990}\\\Rightarrow 5,12(123)-2,11(101)\\=\dfrac{170\ 537}{33\ 300}-\dfrac{21\ 089}{9\ 990}\\=\dfrac{300\ 721}{99\ 900}$
    d)
    $2,(3).3,(2)+2,(3).5,(8)\\=2,(3).[3,(2)+5,(8)]\\=2,(3).9\\\Rightarrow 2,(3)=2,3333…\\\Rightarrow A=2,3333…\\\Rightarrow 10A=23,3333…\\\Rightarrow 10A-A=23,3333…-2,3333…\\\Rightarrow 9A=21\\\Rightarrow A=\dfrac{7}{3}\\\Rightarrow 2,(3).9\\=\dfrac73\cdot9\\=21$

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222-9+11+12:2*14+14 = ? ( )

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