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

Toán Lớp 8: $\frac{x^2+25y^2}{x^2-25y^2}$ ${-}$ $\frac{10xy}{x^2-25y^2}$

Toán Lớp 8: $\frac{x^2+25y^2}{x^2-25y^2}$ ${-}$ $\frac{10xy}{x^2-25y^2}$

Comments ( 2 )

  1. Giải đáp:
    = {x – 5y}/{x + 5y}
    Lời giải và giải thích chi tiết:
     {x^2 + 25y^2}/{x^2 – 25y^2} – {10xy}/{x^2 – 25y^2}
    = {x^2 + 25y^2 – 10xy}/{x^2 – 25y^2}
    = {x^2 – 2.x.5y + (5y)^2}/{x^2 – (5y)^2}
    = {(x – 5y)^2}/{(x – 5y)(x + 5y)}
    = {x – 5y}/{x + 5y}
    -> Dùng HĐT 2: (a – b)^2 = a^2 – 2ab + b^2
    -> Dùng HĐT 3: a^2 – b^2 = (a – b)(a + b)
    #SunHee

  2. Giải đáp:
     $\dfrac{x²+25y²}{x²-25y²}-\dfrac{10xy}{x²-25y²}$
    $= \dfrac{x²+25y²-10xy}{(x-5y).(x+5y)}$
    $= \dfrac{(x-5y)²}{(x-5y).(x+5y)}$
    $= \dfrac{x-5y}{x+5y}$
     

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