`a)x^2+4x+4=(x+2)^2`
`b)9x^2-12x+4=(3x-2)^2`
`c)x^2+x+1/4=(x+1/2)^2`
`d)1/4a^2-2a+4=(1/2a^2-2)^2`
`e)4y^2-9x^2=(2y-3x)(2y+3x)`
`f)9y^2-1/4=(3y-1/2)(3y+1/2)`
`g)8x^3+8a^3=(2x+2a)(4x^2-4xa+4a^2)`
Sửa đề phần `h` thành:
`**-27y^3=(4x-**)(9y^2+**+**)`
`h)64x^3-27y^3=(4x-3y)(9y^2+12xy+16x^2)`