a) x3+ 2x2 - 3x - 6
= (x3 + 2x2) + (-3x - 6)
= x2 (x + 2) - 3(x + 2)
= (x + 2) (x2 - 3)
b) x2 - 9 - 9y2 - 6xy
bó tay câu b) chưa hok!! mới hok phân tích thành nhân tử cùng biến ak!!
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c) a^2 + b^2 - x^2 - y^2 + 2ab - 2xy
= (a^2 + 2ab+ b^2) - (x^2 + 2xy + y^2)
= (a+b)^2 - (x+y)^2
= (a+b -x-y) (a+b+x+y)
\(b\) \(x^2-9+9y^2-6xy=\)\(\left(x^2-6xy+9y^2\right)-9\)\(=\left(x-3y\right)^2-9\)
\(=\left(x-3y-3\right)\left(x-3y+3\right)\)
\(e.\)\(6x^2-150y^2+60y-6=\)\(=x^2+25y^2+10y-1\)
\(=\left(x-5\right)^2-1=\left(x-5-1\right)\left(x-5+1\right)\)