Toán Lớp 8: Phân tích đa thức thành nhân tử :
a. x^3 – 6x^2 + 9x
b. x^2 – 2xy + 3x – 6y
c. x^2 – 8x + 7
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Toán Lớp 8: Phân tích đa thức thành nhân tử :
a. x^3 – 6x^2 + 9x
b. x^2 – 2xy + 3x – 6y
c. x^2 – 8x + 7
Comments ( 2 )
a.{x^3} – 6{x^2} + 9x\\
= x\left( {{x^2} – 6x + 9} \right)\\
= x{\left( {x – 3} \right)^2}\\
b.{x^2} – 2xy + 3x – 6y\\
= \left( {x – 2xy} \right) + \left( {3x – 6y} \right)\\
= x\left( {x – 2y} \right) + 3\left( {x – 2y} \right)\\
= \left( {x – 2y} \right)\left( {x + 3} \right)\\
c.{x^2} – 8x + 7\\
= {x^2} – x – 7x – 7\\
= x\left( {x – 1} \right) – 7\left( {x – 1} \right)\\
= \left( {x – 7} \right)\left( {x – 1} \right)
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