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

Toán Lớp 6: Tìm x: a; 20-[4 mũ 2+(x-6)]=90 b;(x+3).(2.x-4)=o c;1000:[30+(2-6)]= 3 mũ 2 +4 mũ 2 và x thuộc N

Toán Lớp 6: Tìm x:
a; 20-[4 mũ 2+(x-6)]=90
b;(x+3).(2.x-4)=o
c;1000:[30+(2-6)]= 3 mũ 2 +4 mũ 2 và x thuộc N

Comments ( 2 )

  1. Tìm x:
    a,
    20-[4^2+(x-6)]=90
    =>20-[16+(x-6)]=90
    =>16+(x-6)=20-90
    =>16+(x-6)=-70
    =>x-6=-70-16
    =>x-6=-86
    =>x=-80
    Vậy x=-80
    b,
    (x+3).(2x-4)=0
    <=>[(x+3=0),(2x-4=0):}
    <=>[(x=-3),(2x=4):}
    <=>[(x=-3),(x=2):}
    Vậy x=-3;x=2
    c,
    1000:[30+(2^x-6)]=3^2+4^2
    =>1000:(30+2^x-6)=9+16
    =>1000:(24+2^x+6)=25
    =>24+2^x=1000:25
    =>24+2^x=40
    =>2^x=40-24
    =>2^x=16
    =>2^x=2^4
    =>x=4
    Vậy x=4
     

  2. a,
    20-[4^2+(x-6)]=90
    =>20-[16+x-6]=90
    =>20-[10+x]=90
    =>20-10-x=90
    =>10-x=90
    =>x=10-90
    =>x=-80
    Vậy x=-80
    $\\$
    b,
    (x+3).(2x-4)=0
    =>\(\left[ \begin{array}{l}x+3=0\\2x-4=0\end{array} \right.\) 
    =>\(\left[ \begin{array}{l}x=-3\\2x=4\end{array} \right.\) 
    =>\(\left[ \begin{array}{l}x=-3\\x=2\end{array} \right.\) 
    Vậy x=-3; x=2
    $\\$
    c,
    1000:[30+(2^x-6)]=3^2+4^2
    =>1000:[30+2^x-6]=9+16
    =>1000:(24+2^x)=25
    =>24+2^x=1000:25
    =>24+2^x=40
    =>2^x=40-24
    =>2^x=16
    =>2^x=2^4
    =>x=4
    Vậy x=4

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