Evaluate the expression for the given value of the variable(s) 4(3h-6)/1+h; h=-2

= 4(3(-2) -  6) / (1 + (-2))

= 4* -12 /  -1

= -48 / -1

= 48 Answer

Did you mean the derivative of (cos x)^x ? Then, use logarithmic differentiation:

y = (cos x)^x
ln(y) = ln[(cos x)^x]
ln(y) = x * ln[cos x]
(1/y) * y' = 1* ln[cos x] + x * (-sin x)/(cos x)
y' / y = ln[cos x] - (x sin x)/(cos x)
y' = y* [ ln[cos x] - (x sin x)/(cos x) ]

the key step in the process - the substitution.
You had: y = (cos x)^x, so we will substitute for y.

y' = (cos x)^x* [ ln[cos x] - (x sin x)/(cos x) ]
(and this is your final answer)