Find f prime of a....

f (x) = (4)/(sqrt(1-x))

Please Help. I would really appreciate it!

f(x) = 4/sqrt(1 - x)
f(x) = 4/(1 - x)^1/2
f(x) = 4(1 - x)^(-1/2)

Now use a combination of the product rule and chain rule:

f'(x) = 4*(-1/2)*((1 - x)^(-3/2))*(-1) + ((1 - x)^(1/2))*0
f'(x) = 2(1 - x)^(-3/2)

if, for some reason, a fraction is wanted

f'(x) = 2/sqrt((1 - x)^3)