Question

find dy/dx if y= (cos x) ^ x

Answer 1

y = (cos x)^x
log y = log (cos x)^x = x log (cos x)
1/y dy/dx = x * 1/cos x * -sin x + log (cos x) = -xsin x / cos x + log (cos x) = log (cos x) - xtan x
dy/dx = y(log (cos x) - xtan x) = (cos x)^x (log (cos x) - xtan x)