The given function is f( x )=logx.
Differentiate the function with respect to x.
f ′ ( x )= d dx logx = 1 x
It is clear that when x>0,
f ′ ( x )>0 1 x >0
Thus, the function f( x )=logx is strictly increasing in the interval ( 0,∞ ).
Prove that function f given by f(x)=log(cos x) is strictly decreasing on (0,π2) and strictly increasing on (π2π).
Prove that the function f given by f(x) = log sin x is strictly increasing on and strictly decreasing on