# Calculus

posted by
**sh**
.

Find the linear approximation L(x) of the given function at a, and use it to approximate the function value at the given x-value.

f(x)=x^(1/3), a=-27, x=-28

I found the derivative to be

f'(x)= 1/[3(-27)^(2/3)]

but it does not exist because a number cannot be negative in a root.