Toán Lớp 8: Phân tích đa thức thành nhân tử
a) 6x² – 9xy
b) x² – 2xy + 5x – 10y
c) x² – 6x – 25y² + 9
Giúp mình ik hứa vote 5 sao
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Toán Lớp 8: Phân tích đa thức thành nhân tử
a) 6x² – 9xy
b) x² – 2xy + 5x – 10y
c) x² – 6x – 25y² + 9
Giúp mình ik hứa vote 5 sao
Comments ( 2 )
Giải đáp:
$a) 6x^2-9xy$
$= 3x.2x-3x.3y$
$= 3x.(2x-3y)$
$b) x^2-2xy+5x-10y$
$= x.(x-2y)+5.(x-2y)$
$= (x+5).(x-2y)$
$c) x²-6x-25y²+9$
$= (x²-6x+9)-(5y)²$
$= (x-3)²-(5y)²$
$= (x-3+5y).(x-3-5y)$
a) 6x² – 9xy
=3x(2x-3y)
b) x² – 2xy + 5x – 10y
=(x^2-2xy)+(5x-10y)
=x(x-2y)+5(x-2y)
=(x-2y)(x+5)
c) x² – 6x – 25y² + 9
=(x^2-6x+9)-25y^2
=(x-3)^2-(5y)^2
=(x-3-5y)(x-3+5y)