Find the intervals of decrease and increase for the function `f(x)=cos(pi/x)`

Find the interval of increase and decrease for the function g(x) =2f((x^(2))/(2)) +f((27)/(2)-x^(2)) where f''(x) lt 0 " for all " x in R

Find the intervals in which the function f(x)=log(1+x)-(2x)/(2+x) is increasing or decreasing.

Find the intervals in which the function f given by f(x)=(4sinx-2x-xcosx)/(2+cosx)i s increasing decreasing, x in (0,2pi)

Find the intervals in which the function f given by f(x)=sinx+cosx ,\ \ 0lt=x\ lt=2pi is strictly increasing or strictly decreasing.

Find the intervals in which the function f given by f(x)=sinx+cosx ,\ \ \ \ \ \ \ \ \ \ \ \ \ \ 0lt=x\ lt=2pi is strictly increasing or strictly decreasing.

Find the intervals in which the function f given by f(x)=(4sinx-2x-x cox)/(2+cos x) is (i) increasing (ii) decreasing.

Find the intervals in which the function f given f(x)=\ sin x+cosx ,\ 0lt=x\ lt=2pi,\ is strictly increasing or strictly decreasing.

Find the interval in which the function f given by f(x)=sin2x+cos2x, 0lexlepi is strictly decreasing.

Find the intervals in which the function f(x)=2x^3+9x^2+12 x+20 is (i) increasing (ii) decreasing

Find the intervals in which the function f(x) = 2x^(3)-15x^(2)+36x + 6 is (i) increasing, (ii) decreasing.