Question

Answer 1

Bài `3:`

`a)x^2-9+2x+6=0`

`<=>x^2+2x+1-4=0`

`<=>(x+1)^2=4`

`<=>|x+1|=2`

`<=>[(x+1=2),(x+1=-2):}<=>[(x=1),(x=-3):}`

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`b)x^2+9=6x`

`<=>x^2-6x+9=0`

`<=>(x-3)^2=0`

`<=>x-3=0`

`<=>x=3`

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`c)x^3-3x^2+3x-1=8`

`<=>x^3-3x^2+3x-9=0`

`<=>x^2(x-3)+3(x-3)=0`

`<=>(x-3)(x^2+3)=0`

  Mà `x^2+3 > 0 AA x`

  `=>x-3=0`

`<=>x=3`

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`d)4x^2-9+(2x+3)^=0`

`<=>(2x-3)(2x+3)+(2x+3)^2=0`

`<=>(2x+3)(2x-3+2x+3)=0`

`<=>4x(2x+3)=0`

`<=>[(x=0),(x=-3/2):}`

Answer 2

giup minh bai 3 voi