Question

Giải giúp với ạ

Answer 1

b: =>x-7=0 hoặc 5x+2=0

=>x=7 hoặc x=-2/5

d: =>2x+1=0 hoặc x-1=0

=>x=1 hoặc x=-1/2

f: =>(3x+3-x+1)(3x+3+x-1)=0

=>(2x+4)(4x+2)=0

=>x=-1/2 hoặc x=-2

Answer 2

`b)`

`(x-7)(5x+2)=0`

`Th1`

`x-7=0`

`=>x=0+7`

`=>x=7`

`Th2`

`5x+2=0`

`=>5x=-2`

`=>x=-2/5`

`d)`

`(2x+1)(x-1)=0`

`Th1`

`2x+1=0`

`=>2x=-1`

`=>x=-1/2`

`Th2`

`x-1=0`

`=>x=0+1`

`=>x=1`

`f)`

`(x-1)^2=9(x+1)^2`

`<=> (x-1)^2- (3x+3)^2=0`

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

`Th1`

`4x+2=0`

`=>4x=-2`

`=>x=-1/2`

`Th2`

`-2x-4=0`

`=>-2x=4`

`=>x=-2`