3, x^2 + 4x -y^2 + 4 4, 3x^2 -3xy + 5y -5x 5, 3x^2 + 6xy + 3y^2 – 3z^2 6, x^2 – xy + x -y 7, 9x – x^3 PTĐTTNT

0 bình luận về “3, x^2 + 4x -y^2 + 4 4, 3x^2 -3xy + 5y -5x 5, 3x^2 + 6xy + 3y^2 – 3z^2 6, x^2 – xy + x -y 7, 9x – x^3 PTĐTTNT”

1. `x^2 + 4x -y^2 + 4`

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

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

   `3x^2-3xy + 5y -5x`

   `=3(x-y)x-5(x-y)`

   `=(x-y)(3x-5)`

   `3x^2 + 6xy + 3y^2 – 3z^2`

   `=3(x^2+2xy+y^2-z^2)`

   `=3[(x+y)^2-z^2]`

   `=3(x+y-z)(x+y+z)`

   `x^2 – xy + x -y`

   `=x(x-y)+(x-y)`

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

   `9x – x^3`

   `=x(9-x​^2)`

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

    

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2. Đáp án:3. x²+4x-y²+4

   =x²+4x+4-y²=(x+2)²-y²=(x+2-y)(x+2+y)

   4. 3x²-3xy+5y-5x=3x(x-y)-5(x-y)

   =(x-y)(3x-5)

   5. 3x²+6xy+3y²-3z²=3(x²+2xy+y²-z²)

   =3[(x+y)²-z²]=3(x+y-z)(x+y+z)

   6. x²-xy+x-y=x(x-y) +(x-y)

   =(x-y)(x+1)

   7. 9x-x³=x(9-x²)

   =x(3-x)(3+x)

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