Đáp án + Giải thích các bước giải:
a)
`(x/2-2y)^2`
`=>(x/2)^2-2*x/2*2y+(2y)^2`
`=>(x^2)/4-2xy+4y^2`
b)
`(3x+4y)^2`
`=>(3x)^2+2*3x*4y+(4y)^2`
`=>9x^2+24xy+16y^2`
c)
`x^2+x+1/4`
`=>x^2+2*x*1/2+(1/2)^2`
`=>(x+1/2)^2`
d)
`4-(a+b)^2`
`=>2^2-(a+b)^2`
`=>(2-a-b)(2+a+b)`
e)
`(4-y)^2`
`=>4^2-2*4y+y^2`
`=>16-8y+y^2`
f)
`(x-2y)(x+2y)`
`=>x^2-(2y)^2`
`=>x^2-4y^2`