Đáp án + Giải thích các bước giải:
`15.` `(0,01-xy)^3=(0,01)^3-3*(0,01)^2*xy+3*0,01*(xy)^2-(xy)^3`
`=(1/100)^3-3*(1/100)^2*xy+3*1/100*x^2y^2-x^3y^3`
`=1/1000000-3*1/10000*xy+3/100*x^2y^2-x^3y^3`
`=1/1000000-3/10000xy+3/100x^2y^2-x^3y^3`
`19.` `(0,01+xy)^3`
`=(1/100+xy)^3`
`=(1/100)^3+3*(1/100)^2xy+3*1/100*(xy)^2+(xy)^3`
`=1/1000000+3*1/10000xy+3/100x^2y^2+x^3y^3`
`=1/1000000+3/10000xy+3/100x^2y^2+x^3y^3`.
