Question

tìm x biết:

A,(x+2)(x+3)-(x-2)(x+5)=0

B,(12x-5)(4x-1)+(3x-7)(1-16x)=81

C,(2x+3)(x-4)-(x-5)(2x-8)=45

Answer 1

`a)(x+2)(x+3)-(x-2)(x+5)=0`

`<=>x^2+3x+2x+6-x^2-5x+2x+10=0`

`<=>2x=-16`

`<=>x=-8`

Vậy `S={-8}`

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`b)(12x-5)(4x-1)+(3x-7)(1-16x)=81`

`<=>48x^2-12x-20x+5+3x-48x^2-7+112x=81`

`<=>83x=83`

`<=>x=1` 

Vậy `S={1}`

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`c)(2x+3)(x-4)-(x-5)(2x-8)=45`

`<=>2x^2-8x+3x-12-2x^2+8x+10x-40=45`

`<=>13x=97`

`<=>x=97/13`

Vậy `S={97/13}`

Answer 2

a: \(\Leftrightarrow x^2+5x+6-x^2-3x+10=0\)

=>2x+16=0

=>x=-8

b: =>\(48x^2-12x-20x+5+3x-48x^2-7+112x=81\)

=>83x-2=81

=>x=1

c: =>\(2x^2-8x+3x-12-2x^2+8x+10x-40=45\)

=>13x-52=45

=>13x=97

=>x=97/13