Đáp án + Giải thích các bước giải:
`a//A=(-8)xx25xx(-2)xx4xx(-5)xx125`
`->A=-(8xx25xx2xx4xx5xx125)`
`->A=-[(8xx125)xx(4xx25)xx(2xx5)]`
`->A=-(1000xx100xx10)`
`->A=-1000000`
`b//B=19xx25+9xx95+19xx30`
`->B=19xx25+9xx5xx19+19xx30`
`->B=19xx25+45xx19+19xx30`
`->B=19xx(25+45+30)`
`->B=19xx100`
`->B=1900`