Show that the function x³ - 3x -5 has exatly one root for x belongong to (0,5)

hi,

 let f = x³ - 3x -5 

f(0) = -5  & f ( 5 ) = 105

df/dx = 0  @ x=1

 function is decrasing in (0,1 ) & increasing in (1,5 ) .   it will lie below the x axis in (0,1) & will cross the x-axis only once in (1,5 ) , since it is strictly increasing in this region, so there will be only one root