\(a,=x^3+3x^2-6x^2-18x+3x+9=x^3-3x^2-15x+9\\ b,=3x^3-15x^2\\ c,=y^3-2y^2+y^2-2y+3y-6=y^3-y^2+y-6\\ d,=-4x+6x^2\)
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a, (x+3).(x2-6x+3)
= x.(x2-6x+3)+3.(x2-6x+3)
= x3-6x2+3x+3x2-18x+9
=x3-3x2-15x+9
b, 3x.(x2-5x)
= 3x3-15x2
c,(y2+y+3).(y-2)
=(y2+y+3).y + (y2+y+3). (-2)
= y3+y2+3y-2y2-2y-6
\(d,\left(6-9x\right)\left(-\dfrac{2}{3}x\right)\)
= \(-4x+6x^2\)
Hoctot
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