Đề bài: Phân tích đa thức thành nhân tử a) 4x ² + 4x + 1= b) (6x + 3) – (2x – 5) (2x + 1)= c) (5x + 4) ² – 49x ²= d) $x^{4}$ + 2$x^{3}$ – 2x – 4= e) 1

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1. a)4x² + 4x+1

   =(2x)²+2.2x.1+1²

   =(2x+1)²

   b)(6x+3)-(2x-5)(2x+1)

   =3(2x+1)-(2x-5)(2x+1)

   =-2(2x+1)(x+1)

   c)(5x+4)²-49x²

   =(5x+4-7)(5x+4+7)

   =(5x-3)(5x+11)

   d)$x^{4}$ + 2x³ – 15y² + 6z

   =x³(x+2)-x(x+2)

   =x(x²-1)(x+2)

   =x(x-1)(x+1)(x+2)

   e)15xy³ – 2yz – 15y² + 6z=(câu này mk ko bt làm)

   f)9(2x+3)² – 4(x+1)²=9(4x²+12x+9) – 4(x²+2x+1)

   =36x²+108x+81-4x²-8x-4

   =32x²+100x + 77

   =(32x² + 44x) + (56x + 77)

   =4x(8x+11)+7(8x+11)

   =(4x+7)(8x+11)

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2. a) `4x^2+4x+1=(2x+1)^2`

   b) `(6x+3)-(2x-5)(2x+1)`

   `=3(2x+1)-(2x-5)(2x+1)`

   `=-2(2x+1)(x+1)`

   c) `(5x + 4)^2 – 49x^2`

   `=(5x+4)^2-(7x)^2`

   `=(5x+4-7x)(5x+4+7x)`

   `=(-2x+4)(12x+4)`

   d) `=x^4+2x^3-2x-4`

   `=(x^4+2x^3)-(2x+4)`

   `=x^3(x+2)-2(x+2)`

   `=(x+2)(x^3-2)`

   f) ` 9 (2x+3)^2 – 4(x+1)^2`

   `=9(4x^2+12x+9) – 4(x^2+2x+1)`

   `=36x^2+108x+81-4x^2-8x-4`

   `=32x^2+100x + 77`

   `=(32x^2 + 44x) + (56x + 77)`

   `=4x(8x+11)+7(8x+11)`

   `=(4x+7)(8x+11)`

    

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