Question

Answer 1

A).Tham Khảo

Ta có: (−2x+1)(x+3)+(x+1)(2x−1)=14(−2x+1)(x+3)+(x+1)(2x−1)=14

⇔−2x2−6x+x+3+2x2−x+2x−1=14⇔−2x2−6x+x+3+2x2−x+2x−1=14

⇔−4x=12⇔−4x=12

hay x=-3

B).........................

Answer 2

`a)(1-2x)(x+3)+(x+1)(2x-1)=14`

`<=>x+3-2x^2-6x+2x^2-x+2x-1=14`

`<=>-4x=12`

`<=>x=-3`

Vậy `S={-3}`

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`b)(3x^2+x+2)-(2x+1)(2+x)-(x+4)(x-5)=5`

`<=>3x^2+x+2-4x-2x^2-2-x-x^2+5x-4x+20=5`

`<=>-3x=-15`

`<=>x=5`

Vậy `S={5}`