Phân tích thành nhân tử 1) 3x ² – 4x+1 2) 5x ²-7x+2 3)4x ²+9x+5 4) x ²+8x+7 5)6x² -5x-6 6) -10x²-x+3

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1. Đáp án:

    

   Giải thích các bước giải:

   1, $3x^2 -3x -x+1$

    =$ 3x(x-1)-(x-1)$

    =$(x-1)(3x-1)$

   2,$5x^2-7x+2$

    =$5x^2-5x-2x+2$

    =$5x(x-1)-2(x-1)$

    =$(x-1)(5x-2)$

   3,$4x^2+9x+5$

    =$4x^2+4x+5x+5$

    =$4x(x+1)+5(x+1)$

    =$(x+1)(4x+5)$

   4,$x^2+8x+7$

    =$x^2+x+7x+7$

    =$x(x+1)+7(x+1)$

    =$(x+1)(x+7)$

   5,$6x^2-5x-6$

    =$6x^2-9x+4x-6$

    =$3x(2x-3)+2(2x-3)$

    =$(2x-3)(3x+2)$

   6,$-10x^2-x+3$

    =$-10x^2+5x-6x+3$

    =$-5x(2x-1)-3(2x-1)$

    =$(2x-1)(-5x-3)$=$-(5x+3)(2x-1)$

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2. $\text{1) 3x² – 4x + 1.}$

   $\text{= 3x² – 3x – x + 1.}$

   $\text{= 3x(x – 1) – (x – 1).}$

   $\text{= (3x – 1).(x – 1).}$

   $\text{2) 5x² – 7x + 2.}$

   $\text{= 5x² – 5x – 2x + 2.}$

   $\text{= 5x(x – 1) – 2(x – 1).}$

   $\text{= (5x – 2).(x – 1).}$

   $\text{3) 4x² + 9x + 5.}$

   $\text{= 4x² + 4x + 5x + 5.}$

   $\text{= 4x(x + 1) + 5(x + 1).}$

   $\text{= (4x + 5).(x + 1).}$

   $\text{4) x² + 8x + 7.}$

   $\text{= x² + x + 7x + 7.}$

   $\text{= x(x + 1) + 7(x + 1).}$

   $\text{= (x + 7).(x + 1).}$

   $\text{5) 6x² – 5x – 6.}$

   $\text{= 6x² – 9x + 4x – 6.}$

   $\text{= 3x(2x – 3) + 2(2x – 3).}$

   $\text{= (3x + 2).(2x – 3).}$

   $\text{6) -10x² – x + 3.}$

   $\text{= -10x² + 5x – 6x + 3.}$

   $\text{= -5x(2x – 1) – 3(2x – 1).}$

   $\text{= -(5x + 3).(2x – 1).}$

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