# Calculus

posted by
**Kelly**
.

find f'(a) for f(x)=1/sqrt(13-7x)

i got my answer to be 7 / (7(13-7x)sqrt(13-7x))

but it says i am wrong

please help

posted by
**Kelly**
.

find f'(a) for f(x)=1/sqrt(13-7x)

i got my answer to be 7 / (7(13-7x)sqrt(13-7x))

but it says i am wrong

please help