Toán Lớp 8: Phân Tích thành nhân tử:
a, x^4 + 2x^3 +x^2 c, 5x^2 – 10xy + 5y^2 – 20z^2
b, x^3 – x + 3x^2y^2 + y^3 – y
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Toán Lớp 8: Phân Tích thành nhân tử:
a, x^4 + 2x^3 +x^2 c, 5x^2 – 10xy + 5y^2 – 20z^2
b, x^3 – x + 3x^2y^2 + y^3 – y
Comments ( 2 )
a) x4 + 2×3 + x2
= x2 ( x2 + 2x + 1 )
= x2 ( x + 1 )2
b) 5×2 – 10xy + 5y2 – 20z2
= 5 [(x2 – 2xy + y2 ) – 4z2 ]
= 5 [( x – y )2 – ( 2z )2 ]
= 5 ( x – y – 2z ) ( x – y + 2z )
c) x3 – x + 3x2y + 3xy2+ y3- y
= ( x3 + 3x2y + 3xy2 + y3 ) – ( x + y )
= (x + y )3 – ( x + y)
= ( x + y ) [( x + y )2 – 1 ]
= ( x + y ) ( x + y + 1 ) ( x + y – 1 )