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

Toán Lớp 6: gấp ạ Tìm x a) x – 36 : 18 = 12 – 15 b) 92 – (17 + x) = 72 c) 720 : [41 – (2x + 5)] = 40 d) (x + 2)3 – 23 = 41 e) 70 ⋮ x; 84 ⋮ x; 140

Toán Lớp 6: gấp ạ
Tìm x
a) x – 36 : 18 = 12 – 15
b) 92 – (17 + x) = 72
c) 720 : [41 – (2x + 5)] = 40
d) (x + 2)3 – 23 = 41
e) 70 ⋮ x; 84 ⋮ x; 140 ⋮ x và x > 8

Comments ( 2 )

  1. a) x-36:18 =12.15
      ⇒x-2=-3
      ⇒x=-1
    b)92-(17+x)=72
      ⇒17+x=20
      ⇒x=3
      c)720:[41-(2x+5]=40
      ⇒41-(2x+5)=18
      ⇒2x=18
      ⇒x=9
      

  2. Lời giải chi tiết:
    a) x-36:18=12-15
    =>x-2=-3
    =>x=-3+2
    =>x=-1
    Vậy x=-1
    b) 92-(17+x)=72
    =>17+x=92-72
    =>17+x=20
    =>x=20-17
    =>x=3
    Vậy x=3
    c) 720:[41-(2x+5)]=40
    =>41-(2x+5)=720:40
    =>41-(2x+5)=18
    =>2x+5=23
    =>2x=23-5
    =>2x=18
    =>x=18:2
    =>x=9
    Vậy x=9
    d) (x+2).3-23=41
    =>(x+2).3=41+23
    =>(x+2).3=64
    =>x+2=64:3
    =>x+2=64/3
    =>x=64/3-2
    =>x=58/3
    Vậy x=58/3
    e) 70\vdotsx
    84\vdotsx
    140\vdotsx
    =>x∈ƯC(70,84,140)
    Ta có:
    70=2xx5xx7
    84=2^2xx3xx7
    140=2^2xx5xx7
    =>ƯCLN(70,84,140)=2xx7=14
    =>ƯC(70,84,140)={±1;±2;±7;±14}
    =>x∈{±1;±2;±7;±14}
    Mà x>8 nên x=14
    Vậy x=14
    @uniquetimehunter

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

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