Consider the indefinite integral ${\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}\frac{2y}{1-y^2}dy.$

$(a)$ Evaluate the function with substitution.

$(b)$ Evaluate the integral with partial fraction decomposition.

$(c)$ Did you get the same answer for parts $(a)$ and $(b)?If$ not, what $is$ the correct answer? Explain.