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

Toán Lớp 8: Bài 3: Phân tích các đa thức thành nhân tử: 10) x^2 + x – xy – y 11) x^2 + 4x – 4y^2 + 4 12) x^2 – y^2 + 2x +

Toán Lớp 8: Bài 3: Phân tích các đa thức thành nhân tử:
10) x^2 + x – xy – y 11) x^2 + 4x – 4y^2 + 4 12) x^2 – y^2 + 2x + 1
13) x^2 – x – y^2 – y 14) 5x – 5y + ax – ay 15) x^2 – 2x – 4y^2 – 4y
gấp!!!!!!

Comments ( 2 )

  1. 10, x^2 + x – xy -y
    = x(x+1) – y(x+1)
    =(x+1)(x-y)
    11, x^2 + 4x – 4y^2 +4
    = (x^2 + 4x + 4) – 4y^2
    = (x+2)^2 – (2y)^2
    = (x+2+2y)(x+2-2y)
    12, x^2 – y^2 + 2x+1
    =(x^2 + 2x +1)-y^2
    =(x+1)^2 – y^2
    =(x+1+y)(x+1-y)
    13, x^2 – x – y^2 -y
    =(x^2 – y^2 ) + (-x-y)
    = (x+y)(x-y) – (x+y)
    =(x+y)(x-y-1)
    14, 5x-5y + ax -ay
    = 5(x-y) + a(x-y)
    =(x-y)(5+a)
    15, x^2 – 2x – 4y^2 -4y
    = (x^2 – 4y^2 ) + (-2x-4y)
    =(x+2y)(x-2y) – 2(x+2y)
    =(x+2y)(x-2y-2)
     

  2. 10)$x^2 + x – xy – y$
    $=x(x+1)-y(x+1)$
    $=(x-y)(x+1)$
    11)$x^2 + 4x – 4y^2 + 4$
    $=x^2 + 2.2x + 2^2 – 4.y^2$
    $=(x+2)^2 – (2y)^2$
    $=(x+2 – 2y)(x+2+2y)$
    12)$x^2 – y^2 + 2x + 1$
    $=x^2 + 2x + 1 – y^2$
    $=(x+1)^2 – y^2$
    $=(x^2+2x+1)–y^2$
    $=(x+1)^2−y^2$
    $=(x+1+y)(x+1−y)$
    13)$x^2 – x – y^2 – y$
    $=x^2−x−y^2−y$
    $=x^2−y^2−(x+y)$
    $=(x−y)(x+y)−(x+y)$
    $=(x+y)(x−y−1)$
    14)$5x – 5y + ax – ay$
    $= 5(x – y) + a(x – y)$
    $= (5 + a)(x – y)$
    15)$x^2 – 2x – 4y^2 – 4y$
    $=x^2- 2x – 4y^2- 4y$
    $= ( x^2-4y^2 ) – ( 2x + 4y )$
    $= [x^2 – ( 2y )^2 ] – 2( x + 2y )$
    $= ( x – 2y )( x + 2y ) – 2(x + 2y)$
    $= ( x + 2y )(x + 2y – 2 )$
    Cho 5sao và ctlhn nha 
    chúc học tốt!

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