a: =>x(x^2-1/4)=0

=>x(x-1/2)(x+1/2)=0

=>\(x\in\left\{0;\dfrac{1}{2};-\dfrac{1}{2}\right\}\)

b: =>(x-1)(5x-1)=0

=>x=1/5 hoặc x=1

c: =>(2x-1-x-3)(2x-1+x+3)=0

=>(x-4)(3x+2)=0

=>x=4 hoặc x=-2/3

e: =>(x+1)(x+4)=0

=>x=-1 hoặc x=-4

9: =(x+3)^2-y^2=(x+3+y)(x+3-y)

10: =z(x+y)-2(x+y)=(x+y)(z-2)

11: =(2x+1)^2-(3y)^2

=(2x+1+3y)(2x+1-3y)

12: =(x-y)^2+4(x-y)

=(x-y)(x-y+4)

13; =(x-3y)^2-25z^2

=(x-3y-5z)(x-3y+5z)

a: =>(x+3)(5-2x)=0

=>x=-3 hoặc x=5/2

b: =>(x-3)(5x+20)=0

=>x=-4 hoặc x=3

c: =>(x-2)(5x+1)=0

=>x=2 hoặc x=-1/5

d: =>(x-1)(x+2)=0

=>x=-2 hoặc x=1

e: =>(2x+1)^2=0

=>2x+1=0

=>x=-1/2

f:=>(3x-5)(3x+3)=0

=>x=-1 hoặc x=5/3

18 D

23 C

24 B

1: =2x(x-4)

2: =2(x^2-2x+1)=2(x-1)^2

3: =3x(x^2+4x+4)=3x(x+2)^2

4: =x(x^2-2x+1)=x(x-1)^2

5: =x(x-3)+y(x-3)

=(x-3)(x+y)

7: =(x+1)^2-16y^2

=(x+1+4y)(x+1-4y)