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

Toán Lớp 6: Bài 3. Cho x > y . Tính A, biết: A = -(x + y – z) + (-x + y – z) – (-x – y)

Toán Lớp 6: Bài 3. Cho x > y . Tính A, biết: A = -(x + y – z) + (-x + y – z) – (-x – y)

Comments ( 2 )

  1. A=-(x+y-z)+(-x+y-z)-(-x-y)
    =-x-y+z-x+y-z+x+y
    =[(-x)+x-x]+[(-y)+y+y]+[z-z]
    =(-x)+y+0
    =-x+y
     

  2. $\textit{Lời giải và giải thích chi tiết:}$
    $\textit{Ta có: A = -(x + y – z) + (-x + y – z) – (-x – y)}$
    $\textit{             = -x – y + z – x + y – z + x + y}$
    $\textit{             = (-x – x + x) + (-y + y + y) + (z – z)}$
    $\textit{             = -x – y}$
    $\textit{             = y – x}$
    $\textit{Mà x > y ⇒ y – x < 0}$
    $\textit{⇒ |y – x| = -(y – x) = x – y}$
    $\textit{Vậy |A| = |y – x| = x – y}$

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

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