>>837
lim (sin4x) / x
x→0
=lim(x→0) 4*sin(4x)/(4x)=lim(t→0)4*sint/t =4

lim x(cot3x)
x→0
=lim(x→0) x cos(3x)/sin(3x)=lim(x→0)cos(3x)/( 3sin(3x)/(3x) )
=lim(t→0) cost /( 3*sint/t )=1/3