Find values for a and b such that

$\backslash$lim$\_($x$->0)(($sin$(2$x$))/($x$^(3))+$a$+($b$)/($x$^(2)))=0.$

the question also does not allow l'hopital rule, taylor series and small angle approximation, according to the hint, b must be found first such that the limit $\backslash$lim$\_($x$->0)(1)/($x$^(2))(($sin$(2$x$))/($x$)-2)=-$a$,$knowing that the answer is a$=(4)/(3),$b $=-2,$please help to derive and show steps