Find the derivative of the given function using the limit process:

a) ( f'(x) = {h → 0} {-2x - h}/{x²h + h²} )

b) ( f'(x) = {h → 0} {3}/{2√{3x}(h + √{3x})} )

c) ( f'(x) = {h → 0} {-1}/{x{{3}/{2}}(h + √{3x})} )

d) ( f'(x) = {h → 0} {2x²}/{3h(√{3x} + h)} )