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

Toán Lớp 8: 3/x^2+2xy+y^2 + 4/2xy-x^2-y^2 + 5/x^2y^2

Tháng Mười Hai 18, 2022 Toán học 1 Comment 0 views

Toán Lớp 8: 3/x^2+2xy+y^2 + 4/2xy-x^2-y^2 + 5/x^2y^2

Comments ( 1 )

  1. quynhthanhnhu
    quynhthanhnhu
    18 Tháng Mười Hai, 2022 at 1:44 sáng
    Reply
    $\frac{3}{x^2 + 2xy + y^2}$ + $\frac{4}{2xy – x^2 – y^2}$ +$\frac{5}{x^2 – y^2 }$ 
    = $\frac{3}{(x+y)^2}$ + $\frac{4}{-(2xy – x^2 – y^2)}$ +$\frac{5}{(x – y)(x+y) }$ 
     = $\frac{3}{(x+y)^2}$ $-$ $\frac{4}{( x^2 – 2xy – y^2)}$ +$\frac{5}{(x – y)(x+y) }$ 
    =$\frac{3}{(x+y)^2}$ $-$ $\frac{4}{(x- y)^2}$ +$\frac{5}{(x – y)(x+y) }$ 
    =$\frac{3(x-y)^2}{(x+y)^2(x-y)^2}$ $-$ $\frac{4(x+y)^2}{(x+y)^2(x- y)^2}$ +$\frac{5(x-y)(x+y)}{(x – y)^2(x+y)^2 }$ 
    =$\frac{3(x-y)^2 – 4(x+y)^2 +5(x-y)(x+y)}{(x+y)^2(x-y)^2}$ 
    =$\frac{3(x^2 – 2xy + y^2) – 4(x^2 + 2xy + y^2) +5(x^2 – y^2) }{(x+y)^2(x-y)^2}$ 
    =$\frac{3x^2 – 6xy + 3y^2 – 4x^2 -8xy – 4y^2 +5x^2 – 5y^2 }{(x+y)^2(x-y)^2}$ 
    =$\frac{4x^2 – 14xy – 6y^2 }{(x+y)^2(x-y)^2}$ 
    =$\frac{2(2x^2 – 7xy – 3y^2 ) }{(x^2 – y^2 )^2}$ 
    = $\frac{2(2x^2 – 7xy – 3y^2 ) }{x^4 – 2x^2 y^2 + y^4 }$ 

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

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