Toán Lớp 8: Phân tích đa thức thành nhân tử
30(4-2x)^2+(3x-6)
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Toán Lớp 8: Phân tích đa thức thành nhân tử
30(4-2x)^2+(3x-6)
Comments ( 2 )
30{(4 – 2x)^2} + (3x – 6)\\
= \;30{\left( {2x{\rm{ }}-{\rm{ }}4} \right)^2}\; + {\rm{ }}3\left( {x{\rm{ }}-{\rm{ }}2} \right)\\
= {30.2^2}\left( {x{\rm{ }}-{\rm{ }}2} \right){\rm{ }} + {\rm{ }}3\left( {x{\rm{ }}-{\rm{ }}2} \right)\\
= {\rm{ }}120{\left( {x{\rm{ }}-{\rm{ }}2} \right)^2}\; + {\rm{ }}3\left( {x{\rm{ }}-{\rm{ }}2} \right)\\
= {\rm{ }}3\left( {x{\rm{ }}-{\rm{ }}2} \right)\left[ {40\left( {x{\rm{ }}-{\rm{ }}2} \right){\rm{ }} + {\rm{ }}1} \right]\;\\
= {\rm{ }}3\left( {x{\rm{ }}-{\rm{ }}2} \right)\left( {40x{\rm{ }}-{\rm{ }}79} \right)
\end{array}\]
=30.[2.(2-x)]^2+3x-6
=30.2^2 . (2-x)^2-6+3x
=30.4.(2-x)^2-3.(2-x)
=120.(2-x)^2-3.(2-x)
=(2-x).[120.(2-x)-3]
=(2-x).(240-120x-3)
=(2-x)(237-120x)
=3.(2-x).(79-40x)