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

Toán Lớp 8: phân tích thành nhân tử (x^2+4y^2-5)^2-16(x^2y^2-2xy+1)

Toán Lớp 8: phân tích thành nhân tử (x^2+4y^2-5)^2-16(x^2y^2-2xy+1)

Comments ( 2 )

  1. $(x^2+4y^2-5)^2-16(x^2y^2-2xy+1)$
    $=(x^2+4y^2-5)^2-4^2(xy-1)^2$
    $=(x^2+4y^2-5)^2-[4(xy-1)]^2$
    $=(x^2+4y^2-5)^2-(4xy-4)^2$
    $=(x^2+4y^2-5+4xy-4)(x^2+4y^2-5-4xy+4)$
    $=[(x^2+4xy+4y^2)-(5+4)][(x^2-4xy+4y^2)-(5-4)]$
    $=[(x+2y)^2-9][(x-2y)^2-1]$
    $=[(x+2y)^2-3^2][(x-2y)^2-1^2]$
    $=(x+2y+3)(x+2y-3)(x-2y+1)(x-2y-1)$

  2. (x^2+4y^2-5)^2-16(x^2y^2-2xy+1)
    = (x^2+4y^2-5)^2-16[(xy)^2-2.xy.2+1^2]
    = (x^2+4y^2-5)^2-16(xy-1)^2
    = (x^2+4y^2-5)^2-[4(xy-1)]^2
    = [x^2+4y^2-5-4(xy-1)][x^2+4y^2-5+4(xy-1)]
    = [x^2+4y^2-5-4xy+4][x^2+4y^2-5+4xy-4]
    = [(x-2y)^2 -1][(x+2y)^2-9]
    = (x-2y-1)(x-2y+1)(x+2y-3)(x+2y+3)

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

About Thúy Mai