Find the derivative of the following functions:
a. f(t) = (1)/(t²)
b. f(x) = (2)/(√(x))
c. f(x) = (2x²⁶)/(3) - (5x)/(6) + (2)/(3x) - ∛(x)
d. f(x) = ∛(x) - (1)/(√(x))