Answer
a) $\dfrac{1}{x^2}$
b) $\dfrac{1}{(x+3)^2}$
c) $\dfrac{1}{(x+C)^2}$
Work Step by Step
a) Consider $y^2=\dfrac{1}{x^2}$
Then, $y'=-[(-1) (x^{-2})]=\dfrac{1}{x^2}$
b) Consider $y^2=\dfrac{1}{(x+3)^2}$
Then, $y'=-[(-1)( (x+3)^{-2})]=\dfrac{1}{(x+3)^2}$
c) Consider $y^2=\dfrac{1}{(x+C)^2}$
Then, $y'=-[(-1)] [(x+C)^{-2}]=\dfrac{1}{(x+C)^2}$