Đáp án:
Giải thích các bước giải:
`a)``(x+1/6y+3)²`
`=[(x+1/6)+3]²`
`=(x+1/6)²+2.(x+1/6).3+3²`
`=x²+2.x. 1/6+(1/6)²+6x+1+9`
`=x²+1/3x+1/(36)+6x+1+9`
`=x²+(19)/3x+10`
`b)(x+y+4)(x+y-4)`
`=(x+y)²-4²`
`=x²+2xy+y²-16`
`c)(x+2y+3z)(2y+3z-x)`
`=(2y+3z)²-x²`
`=4y²+12yz+9z²-x²`
`d)(x-y+6)(x+y-6)`
`=x²-(y-6)²`
`=x²-y²+12y-36`
`e)(y+2z-3)(y-2z-3)`
`=(y-3)²-(2z)²`
`=y²-6y+9-4z²`
