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

Toán Lớp 7: x-1/5 = y-2/3 = z-1/4 và 2x-3y-2z = -27

Toán Lớp 7: x-1/5 = y-2/3 = z-1/4 và 2x-3y-2z = -27

Comments ( 1 )

  1. Ta có:
    (x-1)/5 = (y-2)/3 = (z-1)/4
    <=>(2(x-1))/(2.5)=(3(y-2))/(3.3)=(2(z-1))/(2.4)
    <=>(2x-2)/10=(3y-6)/9=(2z-2)/8
    <=>(2x-2-(3y-6)-(2z-2))/(10-9-8)
    <=>(2x-2-3y+6-2z+2)/-7
    <=>((2x-3y-2z)+(-2+6+2))/-7
    <=>((2x-3y-2z)+6)/-7
    <=>(-27+6)/-7
    <=>(-21)/-7
    <=>3
    @ (x-1)/5=3
    <=>x-1=3.5
    <=>x-1=15
    <=>x=16
    @ (y-2)/3=3
    <=>y-2=3.3
    <=>y-2=9
    <=>y=11
    @ (z-1)/4=3
    <=>z-1=3.4
    <=>z-1=12
    <=>z=13
    Vậy (x;y;z)=(16;11;13)
     

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