`(8/15)^2 . (-5/4)^3`
`= 64/225 . -125/64`
`= -125/225`
`= -5/9`
`e, |x| >=0 forall x in RR`.
Dấu bằng xảy ra `<=> x= 0`.
`-> x ne 0 -> |x| > 0`
`->` Đúng
\(\left(\dfrac{8}{15}\right)^2.\left(-\dfrac{5}{4}\right)^3\)
\(=\dfrac{64}{225}.-\dfrac{125}{64}\)
\(=-\dfrac{5}{9}\)
\(e,\) Đúng