Find the interval in which function f(x) = sin x + cos x is strictly increasing or decreasing.

Separate the interval [0,pi/2] into sub intervals in which function f(x)=sin^4(x)+cos^4(x) is strictly increasing or decreasing.

Separate the interval [0,(pi)/(2)] into sub intervals in which function f(x)=sin^(4)(x)+cos^(4)(x) is strictly increasing or decreasing.

Find the intervals in which f(x)=sin3x cos3x,0

Write the interval in which the function f(x)=cos x is strictly decreasing.

Find the interval in which the function f(x)=sinx+cosx, 0lexle2pi is strictly increasing or strictly decreasing.

Find the intervals in which the function f(x)=x^2+2x-5 strictly increasing or decreasing.

Find the intervals in which the function f(x)=(x+1)^3(x-3)^3 strictly increasing or decreasing.

Find the intervals in which the function f(x)=x+1/x strictly increasing or decreasing.