Đáp án+Giải thích các bước giải:
`a)(3-xy^2)^2-(2+xy^2)^2`
`=3^2-2.3.xy^2+(xy^2)^2-[2^2+2.2.xy^2+(xy^2)^2]`
`= 9 - 6xy^2+x^2y^4-4-4xy^2-x^2y^4`
`=(9-4)-(6xy^2+4xy^2)+(x^2y^4-x^2y^4)`
`= 5-10xy^2`
`c) (a-b^2)(a+b^2)`
`=a^2-(b^2)^2`
`=a^2-b^4`
`e) (x-y+6)(x+y-6)`
`=x^2-(y-6)^2`
`=x^2-(y^2-2.y.6+6^2)`
`=x^2-y^2+12y-36`
`g) (2y-5)(4y^2+10y+25)`
`=(2y-5)[(2y)^2+2y.5+5^2]`
`=(2y)^3-5^3`
`=8y^3-125`
`i) (x-3)^3+(2-x)^3`
`=x^3-3.x^2 .3+3.x.3^2-3^3+2^3-3.2^2 .x+3.2.x^2-x^3`
`=x^3-9x^2+27x-27+8-12x+6x^2-x^3`
`=(x^3-x^3)-(9x^2-6x^2)+(27x-12x)-(27-8)`
`= -3x^2+15x-19`
