contestada

If a function is always positive, then what must be true about its derivative? (a) the derivative is increasing (b) the derivative is decreasing (c) the derivative is always positive (d) the derivative is never negative (e) you can't conclude anything about the derivative

Respuesta :

LammettHash
Consider the function [tex]f(x)=x^2+1[/tex], which is always positive. The derivative is

[tex]f'(x)=2x[/tex]

which is negative for [tex]x<0[/tex] and positive for [tex]x>0[/tex]. This example alone tells you that you can't generally describe the sign of the derivative of a strictly positive function, so the answer is E.