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

Toán Lớp 8: Cho x + y = z và x – y = 3z vs z khác 0 tính P = x + 2y – z/3x + 4y

Toán Lớp 8: Cho x + y = z và x – y = 3z vs z khác 0
tính P = x + 2y – z/3x + 4y

Comments ( 2 )

  1. Ta có: $ x = 2z ; y = -z$
    $ P = \text{$\dfrac{x + 2y – z}{3x + 4y} = \dfrac{2z + 2(-z) -z}{3(2z) + 4(-z)} = \dfrac{-z}{2z}$ = $\dfrac{-1}{2}$}$
     

  2. $\\$
    x+y=z
    x-y=3z
    ->x=(3z +z)/2 = (4z)/2= 2z
    Và y=(z-3z)/2 = (-2z)/2=-z
    P=(x+2y-z)/(3x+4y)
    ->P=(2z  -2z – z)/(6z – 4z)
    -> P =(-z)/(2z)
    ->P= (-1)/2
    Vậy P=(-1)/2

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