Giúp ạ

`@` Bài `1:`

`a)`

        `2x+2y-(x+y)^2`

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

`=(x+y).[2-(x+y)]`

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

`b)`

        `9x^2-y^2 +3x+y`

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

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

`=(3x+y)(3x-y+1)`

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`@` Bài `2:`

        `(5-2x)(2x+7)=4x^2 -25`

`⇔(5-2x)(2x+7)+25-4x^2=0`

`⇔(5-2x)(2x+7)+(5-2x)(5+2x)=0`

`⇔(5-2x)(2x+7+5+2x)=0`

`⇔(5-2x)(4x+12)=0`

`⇔4(5-2x)(x+3)=0`

`⇔[(5-2x=0),(x+3=0):}`

 `⇔[(x=5/2),(x=-3):}`

Vậy, `x∈{5/2;-3}`

`#` $Mpro$