Đáp án + Giải thích các bước giải:
g)`3x^2-3y^2-2(x-y)^2=3(x^2-y^2)-2(x-y)^2`
`=3(x-y)(x+y)-2(x-y)^2=(x-y)[3(x+y)-2(x-y)]`
`=(x-y)(3x+3y-2x+2y)=(x-y)(x+5y)`
h)`81x^2-6yz-9y^2-z^2=81x^2-9y^2-6yz-z^2`
`=81x^2-(9y^2+6xy+z^2)=(9x)^2-(3y+z)^2`
`=(9x-3y-z)(9x+3y+z)`
k)`5xy^3-2xyz-15y^2+6z=5xy^3-15y^2-2xyz+6z`
`=5y^2(xy-3)-2z(xy-3)=(xy-3)(5y^2-2z)`
h)`ab^3c^2-a^2b^2c^2+ab^2c^3-a^2bc^3`
`=(ab^3c^2+ab^2c^3)-(a^2b^2c^2+a^2bc^3)`
`=ab^2c^2(b+c)-a^2bc^2(b+c)`
`=(b+c)(ab^2c^2-a^2bc^2)`
