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

Toán Lớp 7: A) X+6 /8 + x+8/6 +x+1/13 +3=0 B) x-5/10 +x-7/8+x-1/14=13 Giúp mk vs ạ

Tháng Mười Hai 16, 2022 Toán học 2 Comments 0 views

Toán Lớp 7: A) X+6 /8 + x+8/6 +x+1/13 +3=0 B) x-5/10 +x-7/8+x-1/14=13 Giúp mk vs ạ

Comments ( 2 )

  1. lyly98
    lyly98
    16 Tháng Mười Hai, 2022 at 2:57 sáng
    Reply
    a) (x+6)/8+(x+8)/6+(x+1)/13+3=0
    ⇔(x+6+8)/8+(x+8+6)/6+(x+1+13)/13=0
    ⇔(x+14)/8+(x+14)/6+(x+14)/13=0
    ⇔(x+14)(1/8+1/6+1/13)=0
    Vậy x+14=0 (vì 1/8+1/6+1/13>0)
    ⇔x=-14
    b)(x-5)/10+(x-7)/8+(x-1)/(14)=3
    ⇔(x-5-10)/(10) +(x-7-8)/8+(x-1-14)/(14)=0
    ⇔(x-15)(1/(10)+1/8+1/(14))=0
    ⇔x-15=0 (Vì (1/(10)+1/8+1/(14))=0
    ⇔x=15

  2. kimlien
    kimlien
    16 Tháng Mười Hai, 2022 at 2:57 sáng
    Reply
    Giải đáp:
     b) Sửa (x-5)/10+(x-7)/8+(x-1)/14=13->(x-5)/10+(x-7)/8+(x-1)/14=3.
    Lời giải và giải thích chi tiết:
     a)(x+6)/8+(x+8)/6+(x+1)/13+3=0
    <=>[(x+6)/8+1]+[(x+8)/6+1]+[(x+1)/13+1]=0
    <=>(x+14)/8+(x+14)/6+(x+14)/13=0
    <=>(x+14)(1/8+1/6+1/13)=0
    <=>x+14=0 do 1/8+1/6+1/13>0
    <=>x=-14
    Vậy x=-14.
    b)(x-5)/10+(x-7)/8+(x-1)/14=3
    <=>[(x-5)/10-1]+[(x-7)/8-1]+[(x-1)/14-1]=0
    <=>(x-15)/10+(x-15)/8+(x-15)/14=0
    <=>(x-15)(1/10+1/8+1/14)=0
    <=>x-15=0 do 1/10+1/8+1/4>0
    <=>x=15
    Vậy x=15.

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

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